Method and system for controlling a heat pump

Abstract

The present disclosure relates to a method (100) for controlling heat flow in a heat pump, the method (100) comprising measuring (110) an output parameter (26) related to the amount of process heat delivered from the heat pump to a consumer, and controlling (120) the amount of input heat delivered to the heat pump based on the measured output parameter (26).

Description

[Technical Field]

[0001] <1. Technical field> The present disclosure relates to methods, apparatus, systems and computer programs for controlling heat pumps that can provide process heat and / or process cooling in applications such as spray dryers in food processing plants. [Background technology]

[0002] <2. Background technology> Heat pumps provide process heating and / or process cooling at high efficiency for a variety of industrial and domestic applications.

[0003] The working principle of a heat pump, such as a mechanical vapor compression heat pump, is based on the expansion, heat absorption, compression, and heat release of a process medium, such as carbon dioxide (CO2). The process medium absorbs heat (at low pressure) on the supply side (heat source) of the heat pump. This allows the process medium to evaporate. On the consumption side (heat sink) of the heat pump, the process medium releases heat. When releasing heat, the process medium is at a higher pressure than on the heat source side. This allows the process medium to condense. This applies to subcritical heat pumps. In supercritical heat pumps, the process medium is substantially cooled without a phase change. Heat pumps typically use a compressor and a throttling valve to drive the pressure change of the process medium.

[0004] Heat pumps require a control method to control, for example, the desired target temperature at the consumer side of the heat pump by adjusting the heat pump's capacity, which can be achieved by varying the compressor's absorbed power in response to different temperatures.

[0005] However, conventional heat pump control methods and systems suffer from various deficiencies. For example, conventional control methods can result in unstable control or insufficient control bandwidth. Furthermore, conventional control methods may require a buffer tank or similar device to compensate for unstable conditions, for example, by decoupling the heat pump's heat production from the heat demand of the consumer. This requires additional installation space and is detrimental to efficiency. Furthermore, conventional heat pumps are often controlled in a way that prevents the heat pump from operating at its optimal performance. This increases the power required to operate the heat pump, increasing operating costs and potentially increasing carbon dioxide emissions. For example, conventional control methods typically result in significant variations in the heat pump's internal operating conditions, such as compressor power. This can cause the heat pump to operate at less than optimal efficiency, adversely affecting performance.

[0006] Furthermore, some conventional heat pump control methods are unable to simultaneously and stably control the temperatures of the high-temperature and low-temperature sides of the heat pump. In this overall context, U.S. Patent Application Publication No. 2002 / 0134095 relates to a refrigerator including: a first passage including a refrigerating section capillary tube and a refrigerating section evaporator connected in series; a second passage including a freezing section capillary tube and a freezing section evaporator connected in series; a selector valve that selectively allows refrigerant condensed by a condenser to flow through either the first passage, the second passage, or both the first and second passages; a variable-speed refrigerating section fan that circulates air in the refrigerating section while the air is in contact with the refrigerating section evaporator; a variable-speed freezing section fan that circulates air in the freezing section while the air is in contact with the freezing section evaporator; and a controller that switches the selector valve when power is supplied to the refrigerator so that refrigerant simultaneously flows through both the first passage and the second passage.

[0007] Furthermore, U.S. Patent No. 7,316,267 relates to an instantaneous water heater using a heat pump including a heat exchanger in which a refrigerant flow path exchanges heat with a water flow path. Tap water is directly introduced into the water flow path, and hot water supplied from the water flow path is used. The water heater includes at least one of the following elements: 1) a load setting device that sets the amount of heating in the heat exchanger and a heating regulator that adjusts the amount of heating according to the amount set by the load setting device; 2) a heater that heats the water flowing through the water flow path in the heat exchanger and the water flowing through the water flow paths before and after the heat exchanger; 3) multiple compressors; and 4) multiple heat pump cycles. This water heater offers excellent water temperature rise, controllability, and efficiency when hot water supply begins.

[0008] Furthermore, U.S. Patent Application Publication No. 2014 / 060092 relates to a method of operating a heat pump dryer including a process air circuit, a heat pump unit having a refrigerant evaporator for cooling the process air, a primary refrigerant condenser for heating the process air, and a secondary refrigerant evaporator located outside the process air circuit and connected between the primary refrigerant evaporator and a compressor of the heat pump unit, and at least one auxiliary fan adapted to impinge an air flow against the secondary heat exchanger.

[0009] In view of the above, there is a need to provide an improved method for controlling a heat pump. In particular, aspects of the present disclosure aim to ameliorate various deficiencies of the prior art outlined above. Summary of the Invention

[0010] <3. Overview> These and other objects are at least partly solved by the subject matter of the independent claims. Optional embodiments are the subject matter of the dependent claims.

[0011] One aspect of the present disclosure relates to a method for controlling heat flow in a heat pump, the method including measuring an output parameter related to the amount of process heat supplied from the heat pump to a consumer, and controlling the amount of input heat supplied to the heat pump based on the measured output parameter.

[0012] As an example, heat flow may refer to the amount of heat that a heat pump absorbs from a heat source and / or one or more heat sources and delivers as usable process heat to one or more consumers (per unit time).

[0013] The process heat can be used by consumers for any kind of heating, e.g., drying food, heating buildings and / or district heating. The output parameters are, e.g., the temperature and / or volumetric flow rate of the process medium, e.g., water, air, oil, etc.

[0014] For example, the input heat is associated with the low-temperature or input side of the heat pump, which operates at a temperature at which the heat pump's process medium (e.g., a refrigerant such as CO2) typically evaporates and absorbs heat from a heat source or heat supply, e.g., a piece of equipment being cooled by the heat pump. The process heat delivered by the heat pump is associated with the high-temperature or output side of the heat pump, which operates at a temperature at which the heat pump's process medium typically cools and releases heat to the heat pump's output fluid. In the case of a subcritical heat pump, the process medium typically cools and condenses, thereby releasing heat to the heat pump's output fluid.

[0015] It should be noted that controlling the amount of input heat supplied to a heat pump is not the same as controlling the operation of the heat pump itself, for example, by changing the compressor's power output level. For example, changing the compressor's power for a given input heat flow to the heat pump changes the portion of the input heat supplied to the heat pump, e.g., how much of it is actually absorbed by the heat pump's process medium. On the other hand, changing the amount of input heat does not directly affect the internal operation of the heat pump, but is equivalent to controlling the heat pump's operating environment, for example, by increasing the temperature and / or volumetric flow rate of the heat source fluid supplied to the input / low-temperature side of the heat pump. Accordingly, aspects of the present disclosure enable more stable, efficient, and / or robust operation of the heat pump. For example, in this aspect, the desired output characteristics of the heat pump, such as the set output temperature, can be achieved more quickly and / or with less fluctuation than, for example, conventional implementations that only change the compressor's power in response to changes in the set output temperature. This method also has the advantage that varying the input heat can both provide a required amount of process heat (at a specified temperature) and process cooling (at a specified temperature). This can be done in a stable manner.

[0016] Furthermore, aspects of the present disclosure may allow a heat pump to maintain stable operation even when the output temperature or heat demand changes. For example, in this aspect, a heat pump, e.g., a compressor, may be operated at a preferred operating condition, e.g., at high efficiency, over a wide range of output characteristics.

[0017] In some applications of the embodiments described herein, the control can advantageously accommodate changes in the temperature levels of the sources or process cooling consumers that provide the heat input to the heat pump.

[0018] Preferably, in the method, controlling the amount of input heat supplied to the heat pump comprises controlling the temperature and / or flow rate of an input fluid providing the input heat to the heat pump.

[0019] Such heat sources may be components, devices, and / or units that are cooled by the heat pump and provide residual and / or waste heat.

[0020] It should be understood that both the temperature and flow rate of the input fluid can be controlled. In a preferred embodiment, the flow rate of the input fluid is constant and the temperature of the input fluid is controlled. This has the advantage that the flow rate of the input fluid does not change substantially, meaning that the input fluid piping dimensions can be designed to improve hydrodynamic performance. This allows for optimal design of components such as piping (which conducts the input fluid) and heat exchangers.

[0021] In some embodiments, the output parameters measured include one or more of output energy flow rate, output power, output mass flow rate, output temperature, output volumetric flow rate, and output flow rate associated with the output fluid of the heat pump.

[0022] The output fluid is the hot-side output fluid of the heat pump and may be supplied to one or more consumers in a fluid cycle separate from the process medium fluid cycle of the heat pump. The consumers may be components, devices, and / or units requiring process heat. Those skilled in the art will understand references to mass flow, volumetric flow, etc. as mass flow rate, volumetric flow rate, etc. Thus, in this specification, mass flow or mass flow rate refers to the mass of a substance per unit time, i.e., SI units [kg / s].

[0023] The output parameter to be measured can be appropriately selected to facilitate determination of the process heat output. Preferably, the output parameter to be measured is a parameter that is easily measurable. The measurement can be performed by a sensor. When the output parameter to be measured is temperature, common examples of sensors include thermocouples or resistance temperature detectors (RTDs). Temperature measurements can be performed using electrical signaling methods. The means for measuring the output parameter can be located in or near the output fluid of the heat pump.

[0024] Parameters such as flow rate and density of the output fluid may be measured.

[0025] It should be appreciated that the measured output parameters can be useful in determining or estimating the amount of process heat delivered by the heat pump. For example, if the mass flow rate, heat capacity, and temperature of the output fluid are known, the amount of heat delivered by the heat pump can be determined or estimated.

[0026] In some embodiments, controlling the amount of heat input comprises adjusting, preferably dynamically, the transfer function and / or set point of a control loop that controls the amount of heat input.

[0027] For example, such a control loop may include sensing the temperature of an input fluid supplying input heat to a heat pump, comparing the sensed temperature to a setpoint to obtain an error signal, and adjusting the temperature of the input fluid based on the error signal, for example, by a P, PI, or PID controller, or using a similar device to control the mixing ratio of multiple fluids at different temperatures.

[0028] Adjusting the transfer function and / or setpoint of such a control loop controlling the heat input has the advantage that the heat input can be adjusted to accommodate a variety of output characteristics (e.g., changes in output temperature or heat demand) in a stable, reliable manner with minimal fluctuations.

[0029] As an example, a consumer may demand more process heat, resulting in a decrease in the temperature of the fluid returned from the consumer to the heat pump. In some instances, the outlet temperature of the heat pump may also be affected. To compensate for this, aspects of the present disclosure adjust, e.g., increase, the setpoint of a control loop configured to control the heat input. The setpoint may be a temperature setpoint. This allows the operation of the heat pump, and in particular the temperature of the heating or cooling provided by the heat pump, to remain stable even when consumer demand fluctuates widely.

[0030] The transfer function can model the output of the control loop for each possible input and can be composed of one or more constants or variables associated with the proportional, integral, and / or derivative elements of the controller. As an example, the transfer function can include a gain factor (e.g., as used for the proportional element of the controller).

[0031] In some embodiments, the above-described method further comprises obtaining one or more of the following additional information: a set point temperature associated with the process heat quantity; a set point temperature associated with the input heat quantity; a thermal parameter associated with the process heat quantity, optionally a measured value thereof; a thermal parameter associated with the input heat quantity, optionally a measured value thereof; a set point value of the heat pump; optionally a set point temperature of the process medium of the heat pump; and an operating parameter of the heat pump, optionally a measured value thereof, preferably a measured value of the power consumption of the heat pump; and controlling the input heat quantity supplied to the heat pump based on the obtained additional information.

[0032] In some aspects, controlling the amount of input heat based on the acquired additional information includes determining an energy balance of the heat pump based on the acquired additional information, predicting input parameters related to the amount of input heat to be supplied to the heat pump based on the determined energy balance, and controlling the amount of input heat based on the predicted input parameters.

[0033] For example, the predicted input parameters can be used as set points for a control loop that controls the amount of heat input.

[0034] The energy balance may include substantially all heat flow and power through the boundary of the control volume corresponding to the heat pump. In particular, the energy balance may include process heat supplied from the heat pump, input heat supplied to the heat pump, and power, such as compressor power, that operates the heat pump.

[0035] The setpoint associated with the heat input may be the temperature setpoint of the input fluid that provides the heat input to the heat pump.

[0036] The thermal parameter related to the process heat quantity, optionally a measured value thereof, and / or the thermal parameter related to the input heat quantity, optionally a measured value thereof, may include heat capacity (e.g., isobaric heat capacity or isothermal heat capacity), mass flow rate, or similar parameters.

[0037] The additional information acquired may include a setpoint for the process medium (e.g., refrigerant) of the heat pump. As an example, this setpoint may be a setpoint related to the temperature of the refrigerant in the evaporator of the refrigerant cycle of the heat pump. Preferably, the setpoint is the setpoint for the suction pressure in a saturated gas state. For example, in such saturated gas conditions, the temperature is preferably the temperature at which water vapor is in thermodynamic equilibrium with the condensed state. Since pressure and temperature are physically related to each other, the temperature at the saturated suction pressure can be derived from the saturated suction pressure. Therefore, the setpoint for the process medium in this specification may also be the setpoint for the temperature at the saturated suction pressure. Since the temperature / pressure at the outlet of the evaporator of the refrigerant cycle helps determine the input heat amount supplied to the heat pump, this setpoint can be related to the input heat amount supplied to the heat pump.

[0038] The operating parameters of the heat pump may include, for example, the capacity, pressure ratio, and / or efficiency of the compressor of the heat pump. The capacity of the compressor may be proportional to the flow rate of the compressor.

[0039] One or more parameters of the energy balance can be obtained as described herein (e.g., using measurements, obtaining a setpoint). The energy balance can be used to predict input parameters, such as, for example, the temperature of the input fluid to the heat pump. This has the advantage that the predicted input parameters can be used to control the amount of heat input. In particular, this allows for improving said input parameters and / or checking process heat side parameters to derive improved input parameters, thereby reducing fluctuations (e.g., fluctuations that may occur when the desired setpoint of a consumer receiving process heat is changed).

[0040] Of particular advantage, the energy balance includes a combination of actual operating values ​​and information relating to future operating values ​​corresponding to the steady state that the heat pump is likely to have, e.g., the temperature setpoint serves as a predictor of the next steady state, while the measured values ​​correspond to the actual values.

[0041] The inventors have found that determining the energy balance as described herein, predicting the input parameters, and obtaining additional information is highly beneficial for controlling (and reducing fluctuations in) the hot side (hot supply temperature and / or heat quantity) and cold side (cold supply temperature) of a heat pump, since most of the relevant parameters are taken into account.

[0042] For example, predicted input parameters include the temperature of the input fluid that provides the input heat to the heat pump.

[0043] This has the advantage that the predicted temperature of the input fluid can be used in the heat flow control methods described herein, which reduces variability and facilitates a fast and robust response when controlling the heat flow of the heat pump.

[0044] Additionally, the methods described herein may include adjusting the transfer function and / or set point of a control loop controlling the thermal input based on the predicted input parameters.

[0045] This further improves the control of the heat flow of the heat pump. In particular, the predicted input parameters are better suited to the control loop controlling the heat input, thus ensuring a more stable and robust control.

[0046] Furthermore, in some embodiments, controlling the amount of input heat further includes supplying a process cooling amount from the heat pump to one or more process cooling consumers, and varying the amount of heat supplied from the one or more process cooling consumers to the heat pump to control the amount of input heat.

[0047] It will be appreciated that the method includes providing process cooling by a heat pump in a combined cooling and heating application. The process cooling serves to cool another medium. The process cooling can be used, for example, in a refrigerator (as a process cooling consumer). The method thereby facilitates providing process heat and process cooling substantially simultaneously.

[0048] It should also be appreciated that the amount of heat supplied by one or more process cooling consumers can be varied, thereby facilitating substantially simultaneous control of the heat input. Thus, variation of process cooling can be coordinated with control of heat pump heat flow.

[0049] The present disclosure also relates to a controller for controlling heat flow in a heat pump, the controller being configured to perform the steps of the methods disclosed herein.

[0050] The present disclosure also relates to a computer program comprising instructions that, when executed by a controller, cause the controller to perform the steps of the methods disclosed herein.

[0051] The present disclosure also relates to a heating system, such as a heating system for a food processing system and / or a district heating system, comprising a controller as described herein, a heat pump, a sensor for measuring an output parameter related to the amount of process heat supplied from the heat pump to a consumer, and an actuator for adjusting the amount of input heat supplied to the heat pump.

[0052] As an example, the method can be employed in a drying plant. In another example, the drying plant comprises a spray dryer. The list of products that can be spray dried is extensive and includes, but is not limited to, dairy, food, chemical, agrochemical, energy, biotechnology, pharmaceutical, healthcare, food additives, food ingredients, microorganisms, proteins, peptides, whey, and many other ingredients, and is applicable to similar products in general. Suitable products can be defined by their drying characteristics, rather than their use or origin.

[0053] The process heat provided by the heat pumps disclosed herein can also be used in district heating systems, also known as heat networks or remote heating, which are systems for distributing, for example, centrally generated heat through a system of insulated piping for residential and / or commercial heating, including space heating and / or hot water.

[0054] By way of example, the process heat provided by the heat pump can be supplied to a heat exchanger of a consumer of the heating system, or the process heat provided by the heat pump can be used directly from the process medium of the heat pump.

[0055] (Heat pump process medium) For example, the process medium of a heat pump may be CO2 (which is advantageous for supercritical processes). The process medium is also referred to as the refrigerant of the heat pump. In one example, control of the heat input is based on a process medium setpoint. This can be understood as a setpoint, such as temperature, related to a pressure measurement (e.g., suction pressure) of the process medium being applied and used to predict an input parameter related to the heat input provided to the heat pump.

[0056] The process medium can be used in the supercritical cycle of a heat pump. In such a supercritical cycle, the medium can be in the supercritical phase when heat is supplied from the heat pump (i.e., the refrigerant is cooled but not necessarily condensed). For example, if heat is absorbed from one or more sources, e.g., cold water, CO2 is in a two-phase (subcritical) phase. In the latter case, input heat is supplied to the heat pump.

[0057] CO2 is advantageous because it is a natural refrigerant with a relatively low environmental impact. CO2 is non-toxic, non-explosive, and non-flammable. Another advantage is that it can readily release heat over a wide temperature range, making CO2 particularly useful for heating streams that require relatively large temperature increases. Such large temperature increases can occur, for example, in spray dryers and / or spray drying processes.

[0058] In one example, using CO2 as a refrigerant in a heat pump can provide useful process heat to consumers at temperatures above about 135° C. Additionally, useful process cooling can be provided to process cooling consumers at temperatures below about 3° C. This can be achieved in a single compression step with relatively high efficiency.

[0059] The refrigerant is not limited to CO2 and may include other refrigerants, as well as refrigerants that operate in other types of cycles, such as reverse Brayton cycles, subcritical cycles, supercritical cycles, cascade cycles, absorption cycles, and / or hybrid absorption-compression cycles.

[0060] It should be noted that method steps described herein, even if not explicitly described as method steps but rather described with reference to an apparatus (or device or system or controller), may include all aspects and / or embodiments described herein. It should also be understood that features and advantages described with reference to an apparatus (or device or system or controller) are equally applicable to method steps, and vice versa. It should also be understood that an apparatus (or device or system or controller) outlined herein may include means for implementing all aspects and / or embodiments outlined herein, even if they are described in the context of method steps. Furthermore, features and advantages described with reference to method steps may also be equally applicable to an apparatus (or device or system or controller).

[0061] Whether described as method steps, computer programs, and / or means (e.g., a controller), the functions described herein may be implemented in hardware, software, firmware, and / or combinations thereof. If implemented in software / firmware, the functions may be stored on or transferred as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium by which a computer program can be transferred from one place to another. A storage medium may be any available medium accessible by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer-readable storage media include RAM, ROM, EEPROM, FPGA, CD / DVD or other optical disk storage, magnetic disk storage or other magnetic storage, or any other medium that can be used to transfer or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Additionally, the controllers described herein may be implemented in hardware, software, firmware, and / or combinations thereof, e.g., by one or more general-purpose or special-purpose computers and / or general-purpose or special-purpose processors.

[0062] <4. Brief explanation of the drawings> Preferred embodiments will now be described by way of example with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0063] [Figure 1] FIG. 1 is a block diagram of a cascade control system including a master controller and a slave controller, according to one aspect of the present disclosure. [Figure 2] FIG. 2 is a more detailed block diagram of a controller module of a cascade control system including a master controller and a slave controller, according to one aspect of the disclosure. [Figure 3] 1 is a schematic diagram of a heating system employing a method according to one aspect of the present disclosure. [Figure 4] 1A-1C illustrate two different operating modes of a cascade control system for a heat pump according to one embodiment of the present disclosure. [Figure 4a] FIG. 5 illustrates one of the operating modes of FIG. 4 with improved performance. [Figure 5] 5A and 5B are further views related to the embodiment of FIG. 4. [Figure 6] 1 is a schematic flow chart of a method according to one aspect of the present disclosure. [Figure 7] 1 is a schematic diagram of a heat pump controlled by a method according to one aspect of the present disclosure. [Figure 8] FIG. 1 illustrates a spray dryer as heating according to one aspect of the present disclosure. [Figure 9] FIG. 9 illustrates the spray dryer of FIG. 8 equipped with a heat pump according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0064] <5. Detailed Description of Drawings> Next, several exemplary aspects of the present disclosure will be outlined, primarily with reference to the figures above. It should be noted that further embodiments are possible, and the following description is provided by way of example only, not by way of limitation. Furthermore, the present disclosure can be used in other aspects not explicitly disclosed below. Furthermore, as detailed below, the described aspects are compatible with each other, and individual features of one embodiment can also be applied to other embodiments.

[0065] Although specific feature combinations are described below with respect to exemplary embodiments of the present disclosure, it should be understood that not all features of the described embodiments need be present to achieve the present disclosure as defined by the subject matter of the claims. The disclosed embodiments can be modified by combining specific features of one exemplary embodiment with one or more features of another exemplary embodiment. Specifically, those skilled in the art will understand that features, components, and / or functional elements of one exemplary embodiment can be combined with technically compatible features, components, and / or functional elements of any other embodiment of the present disclosure, provided that the resulting combination falls within the definition of the present disclosure provided by the claims. Those skilled in the art will also understand that certain features may be omitted to the extent deemed unnecessary.

[0066] Like numbers refer to like elements throughout the drawings and specification. The drawings may not be to scale, and the relative size, proportions, and depictions of elements in the figures may be exaggerated for clarity, illustration, and convenience.

[0067] FIG. 1 is a block diagram of a cascade control system 60 including a master controller 65 and a slave controller 70 according to one aspect of the present disclosure.

[0068] The control system 60 is adapted to control the amount of input heat 10 provided to the heat pump. Such control can be performed using actuators, such as valves configured to adjust the mix ratio of input fluids at different temperatures.

[0069] In some configurations, the master controller 65 receives a heat pump output fluid temperature measurement (referred to herein as a measured output parameter 26 related to process heat quantity), e.g., as a sense-in signal. The master controller 65 can compare this value to the heat pump output fluid temperature setpoint 26, SP (also referred to herein as the setpoint of the output parameter related to process heat quantity). Based on this comparison, the master controller 65 can generate an output signal 66 that is input directly to a slave controller 70 configured to control the temperature of the fluid providing input heat to the cold side of the heat pump. For example, the master controller 65 output signal 66 is used as a dynamic / floating setpoint for the slave controller 70 to which the heat input fluid temperature measurement (referred to herein as a measured input parameter 11 related to input heat quantity) is compared.

[0070] For example, if a heat consumer receiving process heat from the heat pump requires more heat, the temperature of the output fluid may decrease. This decrease in temperature can be measured and sensed by the master controller 65, which then increases the setpoint used by the slave controller 70. This results in an increase in the temperature of the fluid providing input heat to the heat pump in closed-loop operation. Thus, in the illustrated exemplary embodiment, increased heat demand increases heat supply, improving heat pump operation. This allows the temperature and / or amount of process heat provided by the heat pump and the temperature and / or amount of input heat provided to the heat pump to be controlled substantially simultaneously. For example, heating demanded by high-temperature consumers can be provided while simultaneously providing cooling at a temperature usable by low-temperature consumers. This can be done in a stable manner. Furthermore, the internal operating parameters of the heat pump, such as compressor power, can be maintained near their maximum efficiency.

[0071] In other configurations, the output signal 66 of the master controller 65 may be modified via a pseudo-predictive model (PPM). The pseudo-predictive model (PPM) may be part of a prediction module 80, such as a model according to equation (EQ1) described herein. In such configurations, the output 66 of the master controller 65 is not directly input to the slave controller 70, e.g., as a dynamic setpoint, but is first modified based on additional information about the heat pump, its source, and / or its consumers, as described in detail elsewhere herein, particularly with reference to FIG. 2. The modified setpoint of the slave control is indicated as 66′. For example, the temperature setpoint of the slave controller 70 corresponds to a predicted input temperature based on an energy balance to ensure stable operation of the heat pump over a wide range of output characteristics (e.g., as output temperature or heat demand changes). Also, in such configurations, the operation of the heat pump itself is not affected.

[0072] 2 is a more detailed block diagram of a prediction module 80 usable in the cascade control system 60 disclosed herein. Various inputs to the prediction module 80 are shown on the left. The inputs include the output of the master controller 65, a control signal 67, adjustable predictive model parameters α, η, ±β, and γ, as well as additional information / system data 68 about the heat pump and the heating / cooling system in which the heat pump control system operates (such as measurements and / or setpoints obtained from consumers as described elsewhere herein). The control signal 67 can be switched between feeding the output of the master controller 65 directly to the slave controller 70 (with or without an additional boost offset (α)) or using PPM to obtain a modified predicted setpoint for the slave controller 70, which may or may not be boosted (with α).

[0073] In some embodiments, the output of the master controller 65 may be used as an input to the PPM / prediction module 80. Alternatively or additionally, the inputs of the master controller 65, i.e., the measured output parameters 26 and / or the output parameter set points 26, SP, may be used.

[0074] Therefore, it should be noted that the input data from master controller 65 to prediction module 80 may further include measured output parameters 26 and / or output parameter set points 26, SP. Measured output parameters 26 and / or output parameter set points 26, SP may also be provided to prediction module 80 as part of additional information / system data 68.

[0075] Importantly, the additional information / system data 68 (see, e.g., the discussion in Section 3 above) enables the prediction module 80, and thus the PPM, to predictively consider whether and to what extent the heat output required by the consumer and / or the heat input provided by the heat pump's source will change. In this way, the dynamic setpoint input to the slave controller 70, and thereby the heat output provided to the heat pump, can be adjusted to match the predicted system requirements. This avoids fluctuations such as control loop oscillations and other instabilities. This makes the heat pump particularly useful in applications requiring specific temperatures. It also allows the heat pump to operate closer to maximum efficiency.

[0076] 3 is a schematic diagram of a heating system 50 employing a method according to one embodiment of the present disclosure. The heating system 50 includes a controller 60 as described herein. The heating system 50 includes a heat pump 1. The heating system 50 further includes a sensor 25 for measuring an output parameter 26 related to a process heat quantity 20. The heating system 50 also includes an actuator 15 for adjusting an input heat quantity 10 provided to the heat pump 1. For example, the temperature of a cold water flow can be changed so that the process medium of the heat pump 1 absorbs different heat quantities 10. In this example, the actuator 15 is a valve. In particular, the actuator is a three-way valve.

[0077] The exhaust heat exchanger 40 can be connected to the exhaust air flow of the consumer 30, 30' containing residual heat that can be recovered by the exhaust air heat exchanger 40. This allows heat to be transferred from the exhaust air flow to the cold water, so that the return temperature 11 of the input fluid to the heat pump can be influenced by the actuator 15.

[0078] In the figure, the process heat quantity 20 is exemplarily represented by two connection lines 26, 28 between the heat pump 1 and the consumer 30. In one of the two connection lines (e.g., the connection line corresponding to the measured output parameter 26), a fluid, for example hot water, is conducted (supplied) from the heat pump 1 to the consumer 30. In the other (return) connection line 28 of the two connection lines 26, 28, said fluid, for example reduced-temperature return water, is conducted from the consumer 30 to the heat pump 1. The process heat quantity 20 can be determined by the temperature 26, mass flow rate and heat capacity of said fluid. Preferably, the return temperature 28 is also used to determine the process heat quantity 20.

[0079] In the figure, the heat input 10 is represented by two connection lines 11, 12 between the heat pump 1 and the exhaust heat exchanger 40 and / or other supply source 41. In one of the two connection lines (e.g., the connection line corresponding to the measured input parameter 11), a fluid, e.g., a process medium such as water, is conducted from the exhaust heat exchanger 40 and / or other supply source 41 to the heat pump 1 (or, from the perspective of the heat exchanger 40 and / or other supply source 41, back). In the other (supply) connection line 12 (e.g., the connection line corresponding to the low-temperature supply parameter 12), the fluid is conducted from the heat pump 1 to the exhaust heat exchanger 40 and / or other supply source 41. The heat input 10 can be determined by the temperature 11, mass flow rate, and heat capacity of the fluid. Preferably, the supply temperature 12 is also used to determine the heat input 10.

[0080] As shown in the figure, the heating system 50 may optionally comprise a further consumer 30', which may also receive the process heat 20 supplied by the heat pump 1. The heat pump 1 may operate using a process medium, preferably CO2, as a refrigerant. In one example, the control of the heat input may be based on the temperature setpoint of the medium, as explained herein, in particular with reference to the energy balance below.

[0081] (Energy balance) An embodiment of the method of the present disclosure will now be described with reference to FIG. 3 using an energy balance (which may be part of a pseudo-prediction model PPM, which is part of the prediction module 80 referred to herein).

[0082] The method may include determining an energy balance of the heat pump based on the obtained additional information. The energy balance of the heat pump may be expressed as: JPEG2025537536000002.jpg9170

[0083] Q Heatingis the heat energy measured in joules, for example, leaving the heat pump per unit time, and [Q Heating ]=J / s. Losses are negligible or very small (Q Loss ~zero). Q Heating is the process heat supplied by the heat pump to one or more consumers, and Q Cooling W may be the input heat supplied to the heat pump (e.g., heat provided by the process medium, such as the process medium returned from the exhaust heat exchanger 40 and / or other source 41). Compressor is the (electric) power of one or more compressors of the heat pump (e.g., the power required to compress the process medium of the heat pump), and [W Compressor ]=J / s.

[0084] term Q Heating may be equal to the sum of the process heat supplied to each consumer (e.g., in the case of multiple consumers), as follows: JPEG2025537536000003.jpg9170

[0085] term Q Main Q can be the heat (per unit time) supplied to the first consumer 30, such as the main heater, which requires most of the heat output of the heat pump. rest may be heat supplied to one or more second consumers 30'.

[0086] term Q Cooling can be expressed as follows: JPEG2025537536000004.jpg9170

[0087] In the formula, m cold is the mass flow rate (e.g., of the cooling medium water), and c p is the (isobaric) heat capacity of the medium. T rtn,cold is the return temperature (e.g., the temperature of the cooling medium returning from one or more cooling consumers / heat sources 41 towards the heat pump 1), and T sup,cold12 is the supply temperature (e.g. the temperature of the cooling medium leaving the heat pump 1 towards one or more cooling consumers / heat sources 41). The mass flow leaving the heat pump 1 can be directed to a process cooling consumer 41, which can advantageously use this mass flow as process cooling.

[0088] In the above embodiment, the method comprises predicting an input parameter related to the amount of input heat 10 to be supplied to the heat pump 1 based on the determined energy balance.

[0089] A parameter related to the heat input 10 is the temperature of the input fluid, which may be the process medium of the exhaust heat exchanger 40 and / or other sources 41 (cooling consumers).

[0090] The temperature of the input fluid is the return temperature T rtn,cold Using the energy balance described above, the following equation (EQ1) can be obtained, which can be expressed as the cooling medium return temperature T of the input fluid that provides the input heat to the heat pump. rtn,cold It is possible to predict. JPEG2025537536000005.jpg18170

[0091] In the formula, T sup,cold * The asterisk in sup,cold (i.e. the temperature of the cooling medium leaving the heat pump at the cooling consumer 41) is not measured directly, but instead T sup,cold * This means that the saturation temperature at suction pressure (STaSP) of the heat pump process medium / refrigerant can be predicted from the setpoint (assuming stable operation) using the following formula: JPEG2025537536000006.jpg12170

[0092] The setpoint STaSP,SP can be used to control the capacity of one or more compressors of a heat pump. The saturation temperature at suction pressure (STaSP) can be the temperature at which a substance at a particular pressure changes state from liquid to vapor. The term η is the ratio of the setpoint STaSP,SP and T at typical (e.g., steady) operating conditions of the heat pump. sup,cold * This has been found to improve the stability of the method for controlling the heat flow of the heat pump 1. Such an improvement can be achieved by using a direct measurement of the chilled water supply temperature 12 (herein referred to as T sup,cold , i.e., without an asterisk).

[0093] The term α in the above equation may be a further model parameter used in the start-up process (or mode), as described above. For example, α may be a function of the return temperature T rtn,cold This increases the dynamic / floating setpoint of the slave controller by α, thereby increasing the input heat delivered to heat pump 1. If heat pump 1 is not in start-up mode, this term is set to zero, i.e., disabled.

[0094] The remaining term in EQ1, Q * Main and Q * rest is defined as follows: JPEG2025537536000007.jpg20170

[0095] Again, the asterisk indicates Q * Main and Q * restis not determined directly from the measured quantities alone, but is predicted from the temperature setpoint (denoted by T with the subscript "SP") of the corresponding consumer. The temperature setpoint represents the target value of the corresponding consumer, such as the target temperature of the airflow supplying heat to a dryer (see Figure 8) or similar heat consumer. For the prediction, we assume that the consumer is operating at or near steady state, and that the setpoint represents the actual value.

[0096] Equation (EQ1) advantageously utilizes predicted parameters and actual (measured) variables for the next steady state while controlling the system to reach a steady state, and is therefore also called a pseudo-predictive model (PPM).

[0097] In addition, Q * Main In the above formula to find the temperature setting T Main,air,out,SP The heat pump output parameter setting 26,SP(T sup,hot,SP ) can be associated with JPEG2025537536000008.jpg10170

[0098] The above equation is a term γ , which represents the temperature offset between the setpoint of the hot supply temperature of the heat pump and the temperature setpoint of the consumer (main air in this example). * Thus, the consumer setpoint is lower (the offset is positive) compared to the hot supply temperature setpoint. In some embodiments, the hot supply temperature T sup,hot The actual measured value of can be used in the above equation instead of the set value. Furthermore, in some aspects, the term γ * can be understood as the term γ.

[0099] By way of example, the offset may be approximately 10°C, 20°C, 24°C or 30°C. The value of the offset may depend on the components used in and / or adjacent to the heat pump, e.g. heat exchangers, piping efficiency, etc. The (measured / actual / set values ​​of) output parameters 26 are therefore used to control the amount of input heat supplied to the heat pump 1.

[0100] In particular, the present disclosure provides a method for calculating the return temperature T of the cooling fluid according to equation EQ1. rtn,cold This makes it easier to determine dynamic / variable setpoints for the parameter, which can reduce variations as described herein.

[0101] The difference between the outlet side main heater temperature and the inlet side main heater temperature, T Main,air,out -T Main,air,in can be derived from a heater, as shown between "cold air" and "hot air" in the upper left portion of Figure 8, where the main air exchanges heat with hot feed water (not shown), and the main air temperature leaving the heater (Figure 8) is accordingly higher than the outlet air (T Main,air,out ), which flows into the dryer shown in FIG.

[0102] 4 illustrates (in three diagrams) two different modes of operation of a cascade control system 60 for a heat pump 1 according to one embodiment of the present disclosure. The master controller may be configured as described herein (i.e., to receive and compare the temperature measurement of the output fluid with its temperature setpoint).

[0103] Parameters related to the input heat supplied to the heat pump, e.g., return temperature T rtn,cold is used as the setpoint for the slave controller in the cascade control, as described herein. In particular, the return temperature T rtn,cold is predicted from the energy balance applied as PPM between the master and slave controllers in the cascade control according to equation (EQ1), as described herein. This dynamically adjusts the setpoint of the slave controller. This allows the slave setpoint temperature, i.e., temperature T rtn,cold The set value of can be directed to the predicted value based on equation (EQ1).

[0104] The predicted temperature T thus established (in particular using the measured output parameters related to the process heat quantity supplied by the heat pump) rtn,coldThe cooperation between the master and slave controllers has been found to be beneficial for improving the control of heat flow in the heat pump.

[0105] The predicted value T of the above formula (EQ1) rtn,cold can be limited to a range (e.g., ±β) around the measured value. This limit allows for (large) differences between the predicted and actual temperatures and prevents the predicted value from deviating too far from the actual temperature. Thus, this limit can accommodate, for example, heat losses and / or non-constant parameters. For example, the value of β can be approximately 1°C. The model parameter α in equation (EQ1) can be 5°C. The model parameter η in equation (EQ1) can be 1.5°C.

[0106] In Figure 4, the hot supply temperature T sup,hot,SP The setting value has been changed by 5K, from 131°C to 126°C (Example 1) and from 130°C to 125°C (Example 2).

[0107] Two examples are shown for the method described herein, with the solid line representing Example 1 and the dashed line representing Example 2.

[0108] The top graph in Figure 4 shows the response of the master controller, i.e., the hot supply temperature T, which is the temperature related to the amount of process heat delivered by the heat pump. sup,hot (26). Furthermore, the temperature setting value T sup,hot,SP (26,SP) is shown. The central figure shows the response of the slave control, i.e., the temperature T rtn,cold (11) is shown. The figure below shows the valve control response, i.e., the valve opening (%) of the actuator 15 (Figure 2). The valve opening adjusts the mixing ratio of multiple fluids with different temperatures.

[0109] In PPM Example 1 (solid line), the correction term T sup,cold * Instead of the low temperature supply temperature T sup,coldThe actual measured value of (the temperature leaving the heat pump) is used in equation (EQ1). As a result, we can see that the temperature 26 is not stable but fluctuates (i.e., it does not quickly match the setpoint 26,SP). The predicted value of the low-temperature return temperature 11 also fluctuates ("PPM" in Figure 5). Therefore, the slave control setpoint 11,SP fluctuates (center diagram in Figure 4), which in turn fluctuates the master output 26 (top diagram in Figure 4). In Figure 5, an upper limit of 15°C is set to prevent the saturation temperature STaSP at the suction pressure of the refrigerant from reaching 15°C. This may activate a safety feature in the heat pump controller, reducing the compressor's capacity.

[0110] In PPM Example 2 (dashed line), T sup,cold Instead, the term T sup,cold * is adopted in equation (EQ1). As a result, the temperature T sup,hot (26, Example 2) stabilized and a robust curvature was obtained (Fig. 4, upper panel). In particular, the temperature 26 (Example 2) quickly reached its set point 26,SP. Also, the low-temperature return temperature T rtn,cold The predicted value of (11, Example 2) does not change substantially (Fig. 4, center, dashed line). Figure 4a shows PPM Example 2 in more detail.

[0111] Although the inventors do not wish to be bound by any theory, they believe that the difference between Example 1 and Example 2 can be explained as follows.

[0112] Starting from the above equation (EQ1), if we assume that the term α is zero (normal operation, i.e., there is no startup mode), the terms on the right side of equation (EQ1) are the four temperatures (T sup,cold * , T Main , T rest and T Compr ) can be reformulated as JPEG2025537536000009.jpg10170

[0113] The test results showed that among the four temperatures above, temperature T sup,cold* However, the low temperature return temperature T rtn,cold It was found that this temperature contributes most (based on absolute value) to the prediction of T. Therefore, fluctuations in this temperature may have a negative impact on stable operation. Further testing revealed that when PPM Example 1 is adopted, i.e., the cold supply temperature T sup,cold If the actual measured value of temperature T sup,cold fluctuates, resulting in a predicted temperature T rtn,cold It was found that the stability of the slave controller was affected, which resulted in fluctuations in the slave controller's setpoint.

[0114] If PPM example 2 is adopted, that is, the correction value T sup,cold * The temperature is substantially stable when the setpoint of the saturation temperature at the suction pressure STaSP,SP (which can be derived based on pressure measurements of the suction pressure as described herein) is set to 5°C and the value of η is set to 1.5°C. sup,cold * The value of essentially stabilizes at about 6.5°C.

[0115] 6 is a schematic flow chart of a method 100 according to one embodiment of the present disclosure. Optional method steps are indicated in the figure by dashed boxes.

[0116] The method 100 includes a step 110 of measuring an output parameter 26 related to the amount of process heat supplied from the heat pump to a consumer, and a step 120 of controlling the amount of input heat supplied to the heat pump based on the measured output parameter.

[0117] The method advantageously improves the stable operation of the heat pump. For example, it is understood that a buffer tank is not required for heating. The method therefore provides a cost-effective control of the heat pump.

[0118] Optionally, controlling 120 the amount of input heat provided to the heat pump includes controlling 130 the temperature and / or flow rate of an input fluid providing the input heat to the heat pump.

[0119] Optionally, controlling the heat input 120 includes adjusting 140, preferably dynamically, the transfer function and / or set point of the control loop controlling the heat input.

[0120] Optionally, the method 100 further comprises a step 150 of obtaining one or more of the following additional information: a set point temperature associated with the process heat quantity, a set point temperature associated with the input heat quantity, a thermal parameter associated with the process heat quantity, optionally a measured value thereof, a thermal parameter associated with the input heat quantity, optionally a measured value thereof, a set point value of the heat pump, optionally a set point temperature of the process medium of the heat pump, and an operating parameter of the heat pump, optionally a measured value thereof, preferably a measured value of the power consumption of the heat pump; and a step 135 of controlling the input heat quantity supplied to the heat pump based on the obtained additional information.

[0121] Optionally, the step 120 of controlling the amount of input heat based on the obtained additional information comprises a step 160 of determining an energy balance of the heat pump based on the obtained additional information, and a step 170 of predicting an input parameter related to the amount of input heat to be supplied to the heat pump based on the determined energy balance.

[0122] Optionally, the method 100 further includes the step 145 of adjusting the transfer function and / or set point of a control loop controlling the heat input based on the predicted input parameters.

[0123] Optionally, the step 120 of controlling the input heat quantity further comprises a step 180 of supplying a process cooling quantity from the heat pump to one or more process cooling consumers, and a step 190 of varying the amount of heat supplied to the heat pump from the one or more process cooling consumers to control the input heat quantity.

[0124] Referring to Figure 1, the illustrated controller 60 is for controlling heat flow in a heat pump, the controller 60 being configured to perform a method 100 according to the embodiment of Figure 6. In particular, the controller 60 comprises means for storing instructions that, when executed, cause the controller to perform the method of Figure 6.

[0125] FIG. 7 is a schematic diagram of a heat pump 1 controlled by a method according to one embodiment of the present disclosure. The diagram shows the process medium cycle of the heat pump 1. In this example, CO2 is used as the process medium (i.e., as a refrigerant). Chilled water 5a is provided and fed to heat exchanger 5 on the cold side of the heat pump 1. The refrigerant then absorbs heat and evaporates in evaporator 3. The refrigerant is then directed to optional heat exchanger 6"' (where it may be heated, for example, by a portion of the water heated in heat exchanger 6') and compressed in compressor 2. Downstream of compressor 2, the refrigerant is directed to heat exchanger 6" to heat hot water 8. The refrigerant is then directed to heat exchanger 6' to heat hot water 7, and then to another optional heat exchanger 6, where the residual heat of the refrigerant can be used to heat the refrigerant downstream of evaporator 3 (e.g., as a recuperator). Downstream of optional heat exchanger 6, the refrigerant is directed through expansion valve 4. Upon expansion, the refrigerant liquefies. Part of the refrigerant can bypass the evaporator 3 as shown in the figure, although different configurations (e.g., no bypass) are possible. It is also possible to direct part of the hot water 7 to the heat exchanger 6″. This can be an alternative to using the heat exchanger 6.

[0126] The compressor 2 can be operated with approximately 1 kW of power. Also, approximately 2 kW of input heat can be supplied from the chilled water 5a to the refrigerant via the low-temperature side heat exchanger 5 (i.e., the evaporator 3). This provides a total of approximately 3 kW of heat to the hot water 8 and the warm water 7. Because heat is cost-effective, such a heat pump 1 allows for cost-effective heat supply.

[0127] Furthermore, further benefits can be obtained by using the input heat supplied to the refrigerant as process cooling for the chilled water 5a. For example, when a typical heat pump is applied to supply heat to a home, the heat is supplied from outside air. Therefore, the cooling is performed with outside air and there is no additional benefit. On the other hand, integrating the cooling as a useful process cooling could provide additional benefits and open up avenues for increased added value.

[0128] FIG. 8 illustrates a heating system according to one embodiment of the present disclosure. The heating system 50 in this example is a spray dryer that can be used in food processing. Spray dryers (or spray drying processes) are applied to convert liquid and / or slurry feeds into dry powders using a high-temperature medium, such as hot gas. Spray dryers require high drying temperatures to promote solvent evaporation and produce powders with solids contents of, for example, 95% or higher. Drying air conditions must be stable for relatively long periods, such as days or weeks. Air heating is adjusted to achieve the required drying temperature. Due to the high temperatures of air heating (and optional dehumidification), spray drying is very energy intensive. For example, a dairy spray dryer traditionally requires approximately 1.2 kWh of heating per kg of powder when the drying air temperature is in the range of approximately 200°C to 240°C.

[0129] Heating system 50 includes a controller 60 as described herein, a heat pump 1, a sensor for measuring an output parameter related to the amount of process heat, and an actuator 15 for adjusting the amount of input heat provided to the heat pump. Controller 60, heat pump 1, and actuator 15 are shown as boxes.

[0130] The figure shows several consumers, including a drying chamber 30, a static fluidized bed 30', a vibrofluidizer 30", a bag filter 30"' and a nozzle 30"". A vibrofluidizer can be understood as a type of fluidized bed in which mechanical vibration improves the performance of the fluidization process. As an example, a vibrofluidizer may be a plug-flow type vibrating fluidized bed in which the powder layer vibrates on an air distribution plate. All consumers require at least a portion of the process heat. A consumer is also referred to as a subsystem that receives at least a portion of the process heat.

[0131] Therefore, the term Q in the above equation (EQ1) Heating is expanded to include the heat of additional consumers (i.e., Q rest is further expanded as detailed below. JPEG2025537536000010.jpg10170

[0132] Q Main is the heat of the main heater, Q SFB is the heat of the static fluidized bed, Q Nozzle is the nozzle heat, Q Bagfilter is the heat of the bag filter, Q VF is the heat of the vibrofluidizer, Q Reg is the regeneration heat (not shown explicitly in the figure).

[0133] Furthermore, using the energy balance, the following equation (EQ1e) can be obtained, which gives the return temperature T of the input fluid that provides the input heat to the heat pump. rtn,cold It is possible to predict. JPEG2025537536000011.jpg15170

[0134] The terms of equation (EQ1e) are defined as described above for equation (EQ1).

[0135] 9 is a diagram illustrating a spray dryer as the heating system 50 of FIG. 8 equipped with a heat pump 1 according to one embodiment of the present disclosure. The input heat amount 10 supplied to the heat pump 1 and the process heat amount 20 supplied from the heat pump 1 to a consumer are shown. The spray dryer in the figure is a multi-stage dryer (MSD).

[0136] S1 indicates the ice water (or cold water) dehumidification step, where cold water is used to cool the incoming air below its dew point, which removes a significant amount of humidity from the air and makes the drying process more efficient.

[0137] In S2, the air for the vibrofluidizer is cooled, which is advantageous to prevent the powder obtained in the heating system from becoming too warm during further processing (e.g. packaging).

[0138] S3 indicates process cooling and can be used for other process cooling, such as cooling for lactose crystallization and / or cooling milk to maintain freshness.

[0139] In S4, the exhaust air is cooled. This may be done by an exhaust air heat exchanger 40, as shown in Figure 3. Cooling the exhaust air facilitates the supply of input heat 10 to the heat pump 1. For example, by changing the opening of the valve (15 in Figure 3) between the exhaust air heat exchanger (40 in Figure 3) in S4 and the heat pump 1, the chilled water supply temperature can be influenced.

[0140] The high temperature side of heat pump 1 shows a cycle of hot water (~75°C) and hot water (~135°C). The hot water temperature is the temperature designated 26 in Figure 4 and Figure 4a. Due to the physical properties of CO2, more heat is supplied at the low temperature (75°C) than at the high temperature (135°C).

[0141] S5 provides frost protection, which is useful in winter, for example, to keep the air warmer than 0°C to prevent freezing in the ducts.

[0142] In S6, the air used to regenerate the desiccant wheel (a desiccant wheel can be understood as a wheel for drying air) is heated. This allows the air to be drier than with ice water dehumidification. Hot air may be required to regenerate the wheel. The moisture absorbed from the main air by the wheel is removed again as vapor in the regeneration air. The desiccant wheel can dry the air to a lower humidity than the ice water condenser. In this way, both dehumidification means can be used. This arrangement also allows the cooling of the ice water condenser to be advantageously used, improving overall efficiency. Furthermore, the amount of cooling used can be balanced with the amount of heating used.

[0143] In S7 and S8, heat exchangers are shown, some of which use only warm water, not hot water, to heat the spray dryer fluid. Overall, more heat is applied at lower temperatures than at higher temperatures (because more heat is available at lower temperatures than at higher temperatures). Preferably, in each of S7 and S8, one heat exchanger using warm water and one heat exchanger using hot water are applied.

[0144] At S9 an additional heat exchanger for the main air is shown. This is advantageous as the main air for the spray dryer is around 200°C. Normally the heat for this heat exchanger cannot be delivered from heat pump 1. This heat exchanger can also be used to start the spray dryer when heat pump 1 is not yet running at full capacity. As an example, heat pump 1 is not running at full capacity when the exhaust air of S4 is not yet warm enough. It will be appreciated that the control methods described herein require at least a sufficient amount of input heat (for the control valves of the slave controller to adjust the predetermined mix to meet the setpoint temperature of the input fluid to the heat pump).

[0145] Control of the heat pump 1 of this embodiment by the controller 60 is carried out as described herein. The advantages of such control become particularly apparent when the following is considered.

[0146] Spray dryers typically face disturbances in their operating conditions. One common disturbance is weather changes. As the ambient humidity changes, the ice water mass flow rate required for the ice water dehumidifier also changes. If the control method cannot quickly respond to such sudden changes, the spray dryer will operate without sufficient dehumidification for a significant period of time. This has a negative impact on the energy required for heating. If the heat pump cannot stabilize the hot water temperature, more energy will be required to further heat the air stream to operate the spray dryer.

[0147] During start-up, a spray dryer is heated to its operating temperature. If this operating temperature does not meet the requirements (i.e., is too high or too low), product quality will be compromised and production capacity will be reduced. Therefore, fast and accurate control of the spray dryer is important to facilitate rapid factory start-up.

[0148] The method described herein is not limited to the above examples. A further example in which the method is particularly useful is clean-in-place (CIP) applications. CIP is a method for cleaning the interior surfaces of pipes, vessels, equipment, filters, and related fittings without disassembling the components. The advantage of CIP is that hot water at a specified, constant temperature is used only once to clean the components. Furthermore, the method according to the present disclosure can also be used for applications such as washing, batch cooking, blanching, and / or boiling. All of these applications also use hot water, preferably used once. A further example is a dehumidifier and / or dryer that requires a combination of heating and cooling. Preferably, an airflow is cooled to reduce air humidity and then heated to provide a hot airflow with low relative humidity to dehumidify and / or dry the product. Another example is the supply of boiler make-up water. Furthermore, the method described herein can be applied to district heating applications with low return temperatures.

[0149] The foregoing disclosure has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments.

[0150] It will be apparent that the systems and / or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specific control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods are described herein without reference to specific software code. It will be understood that software and hardware can be designed to implement the systems and / or methods based on the description herein.

[0151] Although particular combinations of features are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. Indeed, many of these features can be combined in ways not specifically recited in the claims and / or disclosed in the specification. While each dependent claim set forth below may depend directly on only one claim, the disclosure of various aspects includes each dependent claim in combination with all other claims in the claim set. The phrase "at least one of" listed items refers to any combination of those items, including singular ones. As an example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0152] No element, act, or instruction used herein should be construed as critical or essential unless explicitly stated otherwise. Also, as used herein, the articles "a" and "an" are intended to include one or more items and can be used interchangeably with "one or more." Furthermore, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, and / or combinations of related and unrelated items) and can be used interchangeably with "one or more." Where only one item is intended, "only one" or similar language is used. Also, as used herein, terms such as "has," "have," and "having" are intended to be open-ended terms. As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, or a combination of hardware and software. As used herein, a processor may be implemented in hardware, firmware, or a combination of hardware and software.

[0153] As used herein, the phrase "based on" is not to be construed as referring to a closed set of information, one or more conditions, one or more factors, etc. In other words, the phrase "based on A" (where "A" may be information, a condition, a factor, etc.) shall be construed as "based on at least A," unless otherwise specified.

[0154] As used herein, the term "or" is an inclusive "or" unless a limiting expression is used for the listed alternatives. For example, a reference to "X is based on A or B" shall be interpreted to include within its scope X is based on A, X is based on B, and X is based on A and B. In this regard, a reference to "X is based on A or B" refers to "at least one of A or B" or "one or more of A or B," since "or" is inclusive. Similarly, a reference to "X is based on A, B, or C" shall be interpreted to include within its scope X is based on A, X is based on B, X is based on C, X is based on A and B, X is based on A and C, X is based on B and C, and X is based on A, B, and C. In this regard, a reference to "X is based on A, B, or C" refers to "at least one of A, B, or C" or "one or more of A, B, or C," since "or" is inclusive. As an example of a limiting expression, a reference to "X is based on only one of A or B" shall be construed to include within its scope X being based on A and X being based on B, but not X being based on A and B.

[0155] When reference is made herein to a "component," "unit," "device," etc., this should not be understood as limiting the particular "component," "unit," "device," etc., but encompasses equivalents that may have similar and / or identical functionality.

[0156] The term "fluctuations" of a parameter / value etc. can be understood as any (significant) change of said parameter / value etc. relative to a more or less constant and / or target value. "Fluctuation" can also be understood as a change that occurs over a period of time. A decrease in the "fluctuations" of a parameter / value etc. can be understood as a decrease in said change of the parameter / value etc.

[0157] <6. Code List> 1. Heat pump 2 Compressor 3. Evaporator 4 Expansion valve 5a cold water 5 Heat exchanger (low temperature side of heat pump) 6,6',6",6"' Heat exchanger (high temperature side of heat pump) 7 Hot water 8 Hot water 9 cold water 10 Input heat 11 Measured input parameters (return temperature) 12 (low temperature) supply temperature 15 Actuators 20 Process heat 25 Sensors, e.g., temperature sensors 26 Measured output parameter (supply temperature) 26,SP Measurement output parameter (supply temperature) setting value 28 High temperature return temperature 30,30',30” consumer 30”',30”” Consumer 40 Exhaust heat exchanger 41 Sources, Process Cooling Consumers PPM pseudo-prediction model SP setting value SSP saturated suction pressure STaSP Saturation temperature at suction pressure (temperature at saturation) STaSP,SP Saturation temperature setting at suction pressure (temperature at saturation) 50 Heating System 60 Controller / Control System 65 Master Controller 66 Master controller output (signal) 66' Slave controller modified setting 67 Control Signal 68 System Data 70 Slave Controller 80 Prediction Module 100 ways 110 Measure output parameters related to the amount of process heat supplied from the heat pump to the consumer 120 Controlling the input heat supplied to a heat pump based on measured output parameters 130 Controlling the temperature and / or flow rate of the input fluid that provides input heat to the heat pump 135 Controlling the input heat amount supplied to the heat pump based on the additional information obtained 140 Adjust, preferably dynamically, the transfer function and / or set point of the control loop that controls the heat input. 145. Adjusting, preferably dynamically, the transfer function and / or set point of the control loop controlling the heat input based on the predicted input parameters. 150 Get additional information 160 Determine the energy balance of the heat pump based on the additional information obtained 170 Based on the determined energy balance, predict the input parameters related to the input heat quantity supplied to the heat pump. 180 Supplying process cooling from a heat pump to one or more process cooling consumers 190 Varying the amount of heat supplied to the heat pump from one or more process cooling consumers to control the amount of heat input

[0158] Further embodiments will now be described to facilitate understanding of the present invention.

[0159] 1. A method (100) for controlling heat flow in a heat pump, comprising: measuring (110) an output parameter (26) related to the amount of process heat delivered by the heat pump to a consumer; and controlling (120) the amount of input heat supplied to the heat pump based on the measured output parameter (26).

[0160] 2. A method (100) according to any of the above embodiments, wherein controlling (120) the amount of input heat supplied to the heat pump comprises controlling (130) the temperature and / or flow rate of an input fluid providing the input heat to the heat pump.

[0161] 3. The output parameter (26) to be measured is: output energy flow rate, output power, output mass flow rate, Output temperature, output volume flow rate, and The method (100) according to any of the previous embodiments, including one or more of the output flow rates associated with the output fluid of the heat pump.

[0162] 4. A method (100) according to any of the preceding embodiments, wherein controlling (120) the amount of heat input comprises adjusting (140), preferably dynamically, a transfer function and / or a setpoint of a control loop controlling the amount of heat input.

[0163] 5. Set temperature related to process heat quantity, Set temperature related to input heat, a thermal parameter related to the process heat quantity, optionally its measured value; a thermal parameter related to the heat input, optionally its measurement value; the setpoint of the heat pump, optionally the setpoint temperature of the heat pump's process medium, and - obtaining (150) one or more of the following additional information: operating parameters of the heat pump, optionally measured values ​​thereof, preferably measured values ​​of the heat pump's power consumption; The method (100) according to any of the previous embodiments, further comprising the step of controlling (135) the amount of input heat provided to the heat pump based on the obtained additional information.

[0164] 6. The step of controlling the amount of heat input based on the acquired additional information (120) determining (160) an energy balance of the heat pump based on the obtained additional information; and predicting (170) an input parameter related to the amount of input heat to be supplied to the heat pump based on the determined energy balance.

[0165] 7. The method (100) according to embodiment 6, wherein the predicted input parameters include the temperature of the input fluid providing the input heat to the heat pump.

[0166] 8. The method (100) according to embodiment 4 and embodiment 6 or 7, further comprising the step of adjusting (145) the transfer function and / or set point of the control loop controlling the input heat quantity based on the predicted input parameters.

[0167] 9. The step of controlling the amount of heat input (120) providing process cooling from the heat pump to one or more process cooling consumers (180); The method (100) according to any of the above-mentioned embodiments, further comprising a step (190) of varying the amount of heat supplied to the heat pump from one or more process cooling consumers to control the amount of input heat.

[0168] 10. A controller (60) for controlling heat flow in a heat pump, comprising: A controller (60) configured to perform a method (100) according to any of the above-described first to ninth embodiments.

[0169] 11. A computer program comprising instructions that, when executed by a controller, cause the controller to perform the method (100) according to any of the above-described embodiments 1 to 9.

[0170] 12. A heating system (50) for a food processing system or a district heating system, comprising: A controller (60) according to embodiment 10; Heat pump (1) and a sensor (25) for measuring (110) an output parameter (26) related to the amount of process heat supplied from the heat pump (1) to a consumer (30); A heating system (50) comprising: an actuator (15) for adjusting the amount of heat input supplied to the heat pump (1).

Claims

1. A method (100) for controlling heat flow in a heat pump, comprising: measuring (110) an output parameter (26) related to the amount of process heat supplied from the heat pump to a consumer; and controlling (120) the amount of input heat supplied to the heat pump based on the measured output parameter (26); The method (100) wherein controlling (120) the amount of input heat supplied to the heat pump includes controlling (130) the temperature of the input fluid providing the input heat to the heat pump using a valve configured to adjust the mixing ratio of input fluids of different temperatures.

2. The output parameter (26) to be measured is: output energy flow rate, output power, output mass flow rate, Output temperature, output volume flow rate, and The method (100) of claim 1, comprising one or more of an output flow rate associated with an output fluid of the heat pump.

3. 3. The method (100) according to claim 1 or 2, wherein the step of controlling the heat input (120) comprises the step of adjusting (140), preferably dynamically, a transfer function and / or a set point of a control loop controlling the heat input.

4. a set temperature associated with the process heat quantity; a set temperature associated with the heat input; a thermal parameter related to said process heat quantity, optionally a measurement thereof; a thermal parameter related to said heat input, optionally a measurement thereof; the setpoint of the heat pump, optionally the setpoint temperature of the process medium of the heat pump; and - obtaining (150) one or more of the following additional information: operating parameters of the heat pump, optionally measured values ​​thereof, preferably measured values ​​of the power consumption of the heat pump; The method (100) of any one of claims 1 to 3, further comprising the step of controlling (135) the amount of heat input supplied to the heat pump based on the obtained additional information.

5. The step of controlling the heat input amount based on the acquired additional information (120) includes: determining (160) an energy balance of the heat pump based on the obtained additional information; and predicting (170) an input parameter related to the amount of input heat to be supplied to the heat pump based on the determined energy balance.

6. The method (100) of claim 5, wherein the predicted input parameters include a temperature of an input fluid providing input heat to the heat pump.

7. 7. The method (100) of any one of claims 3 and 5 or 6, further comprising the step of adjusting (145) a transfer function and / or a set point of a control loop controlling the thermal input based on the predicted input parameters.

8. The step of controlling the heat input (120) comprises: supplying process cooling from the heat pump to one or more process cooling consumers (180); The method (100) of any one of claims 1 to 7, further comprising the step (190) of varying the amount of heat supplied to the heat pump from the one or more process refrigeration consumers to control the amount of heat input.

9. A controller (60) for controlling heat flow of a heat pump, comprising: A controller (60) configured to perform the method (100) of any one of claims 1 to 8.

10. A computer program comprising instructions which, when executed by a controller, cause said controller to carry out the method (100) of any one of claims 1 to 8.

11. A heating system (50) for a food processing system or a district heating system, comprising: A controller (60) according to claim 9; A heat pump (1) and a sensor (25) for measuring (110) an output parameter (26) related to the amount of process heat supplied from the heat pump (1) to a consumer (30); and an actuator (15) for adjusting the amount of heat input supplied to the heat pump (1).

Images