Methods for operating a heating system

Abstract

The invention relates to a method (200) for operating a heating system (1) which has at least one first heat generator (20), in particular a heat pump, for heating a fluid (2) in a buffer storage tank (10), and wherein the heated fluid (4) circulates between the buffer storage tank (10) and at least one heat consumer (92) by means of a heating circuit (90), and wherein a bypass (99) is provided which allows the fluid (4) flowing back to the buffer storage tank (10) in the heating circuit (90) to be at least partially diverted past the buffer storage tank (10) and supplied to the at least one heat consumer (92) again, and wherein the temperature of the fluid (4) in the buffer storage tank (10) is determined (210).It is proposed that the temperature of the returning fluid be determined (220), and that the returning fluid be directed at least partially via the bypass (99) (230, 240) if the determined temperature of the returning fluid is warmer than a predetermined temperature, in particular the determined temperature of the fluid in the buffer storage (10).

Description

[0001] The invention relates to a method for operating a heating system as well as a heating system, a computer program and a machine-readable storage medium. State of the art

[0002] Heating systems with heat generators and buffer storage tanks are known. It is also known that there are heat generators, especially heat pumps, whose return temperature must not exceed a predetermined value for efficient operation.

[0003] In particular, the efficiency and utilization rate of such heat generators, especially heat pumps, depend significantly on the return and supply temperatures. To increase efficiency and utilization rate, the return temperature to the heat generator should be as low as possible, ideally below a specified value.

[0004] If the heating system has a buffer storage tank, the return flow to the heat generator comes from this buffer storage tank. In certain situations, the return flow from a heat consumer can be higher than the buffer storage tank temperature, which in turn leads to an increased return flow to the heat generator (e.g., a fresh water station in circulation mode, domestic hot water heating during thermal disinfection, etc.). Disclosure of the invention

[0005] The object of the invention is to provide a method and a device that minimizes the reduction in efficiency and utility in the situations described above.

[0006] To solve the problem, an inventive method for operating a heating system, as well as a heating system, a computer program and a machine-readable storage medium, are proposed.

[0007] A heating system comprises at least one heat generator, in particular a heat pump, for heating a fluid, or a fluid in a buffer storage tank. The heat generator heats the fluid, which is also referred to as the heat transfer medium. The fluid is typically water. The fluid transports heat from the heat generator to a heat consumer.

[0008] Furthermore, the heated fluid is circulated between the buffer storage tank and at least one heat consumer by means of a heating circuit, in particular a fluid circuit.

[0009] Preferably, several heat consumers can be part of the heating circuit. The heat consumers are arranged in series or parallel to each other.

[0010] An advantage of the invention is that the heating circuit has a bypass. The bypass, in particular a bypass line, allows the fluid flowing back in the heating circuit to the buffer storage tank from at least one of the heat consumers and / or from the heating circuit itself to be diverted, at least partially, and in particular substantially completely, around the buffer storage tank and fed back to the at least one heat consumer. By means of the bypass, the returning fluid can be directed past the buffer storage tank and back into the heating circuit.

[0011] In one process step, the temperature of the fluid in the buffer storage tank is determined. Preferably, this determination is carried out using at least one temperature sensor arranged in such a way that it can detect the temperature in the buffer storage tank.

[0012] The invention is characterized in that the temperature of the returning fluid is determined. Advantageously, the returning fluid is at least partially routed via the bypass if the determined temperature of the returning fluid is warmer than a predetermined temperature and / or the determined temperature of the fluid in the buffer storage tank. In particular, the temperature of the fluid in a partial section of the buffer storage tank is determined.

[0013] The advantage is that the fluid in the buffer storage tank maintains an optimal temperature for the efficiency of the heat generator. It also prevents the fluid in the buffer storage tank from being heated by the returning fluid.

[0014] The measures listed in the dependent claims result in advantageous further developments and improvements of the method specified in the main claim.

[0015] An advantageous further development of the method is characterized in that the fluid flowing back, in particular from at least one, and in particular all, heat consumers, is at least partially routed via the bypass. Preferably, the returning fluid is routed substantially completely via the bypass.

[0016] "Essentially complete" here means that the fluid is mostly routed through the bypass, but some fluid may still enter the buffer tank. In particular, leakage flows can cause small amounts of fluid to enter the buffer tank even when the bypass is fully open, especially via a valve. However, these amounts can be disregarded because their heat input is too low.

[0017] Advantageously, the fluid is at least partially routed via the bypass if the temperature difference between the measured temperature of the returning fluid and the measured and / or predetermined temperature of the fluid in the buffer tank exceeds a predefined offset. This is particularly intended to prevent the returning fluid from heating the fluid contained in the buffer tank.

[0018] An advantageous further development is the inclusion of a hysteresis mechanism with at least one predetermined hysteresis value. Preferably, the hysteresis ensures stability, reduces noise, and smooths the switching processes of the valve.

[0019] A further advantageous embodiment is characterized in that the temperature of the fluid in the buffer storage tank is determined by the first and / or second and / or third temperature sensor in the buffer storage tank. Preferably, the temperature is determined by the temperature sensor that is arranged in the area into which the returning fluid flows into the buffer storage tank. Alternatively or simultaneously, the temperature can be determined in the area from which the fluid flows out to the heat generator.

[0020] The invention also relates to a heating system with a measuring and control device which is configured to carry out all process steps of the method according to one of the preceding claims.

[0021] The invention also relates to a computer program that causes a measuring and control device to perform all process steps of the method according to one of the method claims when it is executed on the measuring and control device.

[0022] The invention also relates to a machine-readable storage medium with a computer program stored on it.

[0023] Examples of implementation are shown in the figures and explained in more detail in the following description. They show: Fig. 1 a heating system according to the invention and Fig. 2 a method according to the invention.

[0024] The Fig. Figure 1 shows a heating system 1 according to the invention. The heating system 1 comprises a heat generator 20, a buffer storage tank 10 and a fluid circuit, in particular a heating circuit 90. Furthermore, the heating system 1 comprises a measuring and control device 3.

[0025] The measuring and control device 3 regulates and / or controls the heating system 1. Preferably, the measuring and control device 3 uses the measurement results from sensors, in particular measuring probes, preferably temperature sensors. Temperature sensors 50, 30, 31, 32, and 91 are shown by way of example. Temperature sensors 50 and 91 are configured to detect the temperature of the fluid 2 in the pipe in or on which they are arranged. Temperature sensors 30, 31, and 32 are configured to detect the temperature of the fluid 2 in the buffer storage tank. Preferably, the temperature in the buffer storage tank 10 increases from bottom to top. For example, the first temperature sensor 30 detects 40.3°C, while the second temperature sensor 31 detects 38.1°C, and the third temperature sensor 32 detects 37.5°C.

[0026] The buffer storage tank 10 is filled with a fluid 2, in particular water, preferably treated water. The fluid 2 forms the heat transfer medium. With the aid of the fluid 2, heat generated by the heat generator 20 is transported to a heat consumer 92.

[0027] The buffer storage tank 10 has insulation 4, a standby zone 11, and a preheating zone 12, 13. The preheating zone is divided into a first preheating zone 12 and a second preheating zone 13. A first boundary between the standby zone 11 and the first preheating zone 12 is defined by the height 36 of a first temperature sensor 30. A second boundary between the first preheating zone 12 and the second preheating zone 13 is defined by the height 37 of a second temperature sensor 31. A third temperature sensor 32 is located at a height 38. The boundaries are each indicated by a dashed line within the buffer storage tank.

[0028] The temperature sensors 30, 31 and 32 are connected to a measuring and control device 3.

[0029] In particular, communication between the temperature sensors, the pumps, the heat generator and other components of the heating system 1 takes place via communication lines, especially control lines, which are shown as dotted lines in the figures.

[0030] According to a further development, only one temperature sensor is installed in or on the buffer storage tank 10. Specifically, the temperature of the fluid 2 in the buffer storage tank 10 is measured by only one temperature sensor. Preferably, the temperature of only one temperature sensor is evaluated. In particular, the temperature of the sensor located in the area of ​​the inlet for the fluid flowing back from the heat consumer 92 and / or in the area of ​​a sampling point 101 is evaluated. The sampling point 101 of the buffer storage tank 10 is explained in more detail below.

[0031] The heat generator 20 is preferably designed as a heat pump, specifically as an air-to-water or water-to-water heat pump. The heat generator can also be designed as a condensing boiler, oil burner, solar thermal system, fuel cell heating system, pellet stove, or air conditioner. The heat generator designed as a heat pump has a refrigeration circuit with a compressor, an expansion valve, and at least two heat exchangers.

[0032] The heat generator 20 is designed to heat the fluid 2 in the buffer storage tank 10.

[0033] According to a first embodiment (not shown), the heating of the fluid 2 in the buffer storage tank 10 can be achieved, in particular, by means of a heat exchanger, which transfers the heat generated by the heat generator 20 to the fluid 2 in the buffer storage tank. Preferably, a heat exchanger is provided in the buffer storage tank 10 for this purpose. Such a design is described in the Fig. 2 not shown. In particular, in such a design, the fluid flowing through the heat generator 20 and the fluid 2 in the buffer storage tank 10 are separated from each other. Preferably, the temperature sensor for detecting the temperature of the fluid in the tank is arranged in the area of ​​the heat exchanger.

[0034] In Fig. Figure 1 shows an exemplary embodiment. The fluid 2 heated by the heat generator 20 flows into the buffer storage tank 10, where it mixes with the fluid 2 contained in the buffer storage tank.

[0035] The heat generator 20 is connected to the buffer storage tank 10 such that a first end of a line 62 is connected to a first draw-off point 101, particularly in the lower region, of the buffer storage tank 10, and the second end of the line 62 is connected to the heat generator 20. Preferably, the draw-off point 101 is located in the second preheating region 13.

[0036] According to an advantageous further development, at least one additional optional temperature sensor 51 is provided in the line 62. The temperature sensor 51 detects the temperature of the fluid flowing back from the buffer storage tank 10 to the heat generator 20.

[0037] A line 60 connects the first heat generator 20 on the outgoing side to a first pump 21. A line 63 connects the first pump 65 to a filling point 103, which leads into the standby area 11 of the buffer storage tank 10. An optional heat generator flow temperature sensor 50 is arranged on or in the line 63. The optional heat generator flow temperature sensor 50 detects the temperature of the fluid leaving the heat generator 20. Preferably, the optional heat generator flow temperature sensor 50 detects the temperature 50 of the fluid 2 in the line 63.

[0038] Preferably, the heat generator 20, the lines 60, 62, 63, and the buffer storage tank 10 form a circuit. The first pump 65 causes circulation within the circuit. According to a further embodiment, the first pump 65 can also be located in line 62 or in the heat generator 20.

[0039] In both embodiments, fluid circulates, among other things, from the heat generator 20 to the buffer storage tank 10 and back to the heat generator 20.

[0040] The measuring and control device 3 is connected to the first heat generator 20, the first pump 65 and the heat generator flow temperature sensor 50.

[0041] Furthermore, fluid from the buffer storage tank 10 circulates through a heating circuit 90, which is explained in more detail below.

[0042] Heating system 1 further comprises a heating circuit 90. At least one heat consumer 92 is installed in heating circuit 90. Fig. Figure 1 shows an example of a heat consumer 92. However, several heat consumers 92 can also be configured, which are arranged in parallel or in series with each other. The heat consumers are part of the heating circuit 90 or are connected to it in such a way that they can extract heat from it.

[0043] A heat consumer 92 is understood to be a unit, in particular an area or body, such as a device or comparable apparatus or a space, which can store thermal energy and transfer it to a medium, such as objects, liquids, or gases. Examples include a radiator, underfloor heating, and the like. A heat exchanger, especially for heating drinking water, also constitutes a heat consumer 92. A drinking water station or drinking water heater can also be a heat consumer 92.

[0044] Heating circuit 90 can also be referred to as a fluid circuit.

[0045] The fluid 2 circulates in the heating circuit 90 from a heating circuit outlet 104 of the buffer storage tank 10 via lines 94, 95, 96 to the at least one heat consumer 92. If several heat consumers 92 are installed, they can be connected in parallel and / or in series with each other in the heating circuit 90.

[0046] The heating circuit 90 comprises the lines 94, 95, 96, 97 and 98. A second pump 93, in particular a circulation pump, pumps fluid 2 from the buffer storage tank 10, in particular from the standby area 11 of the buffer storage tank 10, to one or more heat consumers 92 and back to the buffer storage tank 10.

[0047] For example, in Fig. Figure 1 shows a heat consumer 92. In particular, lines 94 and 95 connect the standby area 11 of the buffer storage tank 10 with the second pump 93.

[0048] The line 96 connects the second pump 93 to at least one heat consumer 92.

[0049] The line 97 connects the heat consumer 92 on the outgoing side to a measuring sensor 91, in particular the return temperature sensor 91.

[0050] Line 98 connects the return temperature sensor 91 to the second preheating section 13. Preferably, lines 97 and 98 form the return line. Lines 94, 95, and 96 form the supply line.

[0051] Preferably, a return temperature sensor 91 is arranged between at least one heat consumer 92 and the buffer storage tank 10. Preferably, the return temperature sensor 91 is located in the return line. In particular, the return temperature sensor 91 detects the temperature of the fluid flowing back to the buffer storage tank 10.

[0052] Both the return temperature sensor 91 and the second pump 93 are connected to the measuring and control device 3. Preferably, the measuring and control device 3 controls both the return temperature sensor 91 and the second pump 93.

[0053] Preferably, a bypass, also referred to as bypass line 99, is provided. The bypass 99 connects the return line, in particular line 98, with the supply line, in particular lines 94 and 95. The bypass 99 allows the fluid flowing back from the heat consumer 92 to bypass the buffer storage tank 10 and be fed at least partially or completely into the heating circuit 90.

[0054] Advantageously, a valve 100 is designed to regulate the fluid flow. For example, valve 100 connects lines 94 and 95 / 96 and 99. For example, a Fig. 1 A three-way valve 100 is provided, which connects lines 94 and 95 / 96 and 99. According to an advantageous embodiment, valves, in particular two-way valves, can also be provided in lines 94, 99, or 98. By blocking or reducing the flow through the line, the fluid 2 is directed through another line. Preferably, several two-way valves can also be provided. For example, one two-way valve can be provided in line 99 and additionally one in line 94 or 98.

[0055] According to a further development, another pump can also be installed, particularly in bypass 99. The second pump 93 can also be installed in the return line or in line 94. Preferably, the second pump 93 is part of the heating circuit 90 and is installed in one of the lines 94, 95, 96, or 97.

[0056] The valve 100 has at least two switching positions. In a first switching position, the valve 100 connects the buffer storage tank 10 to at least one of the heat consumers 92. The fluid is pumped by the second pump 93 from the buffer storage tank 10 to the heat consumer 92 and back to the buffer storage tank 10. The bypass line 99 is closed. The fluid circulates between the buffer storage tank 10 and the heat consumer 92. The valve connects lines 94 and 95.

[0057] In a second switching position of the valve 100, the bypass line 99, lines 95, 96 and parts of lines 97, 98 form a circulation circuit. The second pump 93 circulates the fluid in the heating circuit 90 without it flowing through the buffer tank 10.

[0058] According to further training, the valve 100 can also assume intermediate positions that cause mixing. In particular, in such an intermediate position, fluid from the buffer storage tank 10 would mix with fluid via the bypass line 99. Specifically, with a mixing ratio of 50:50, 50% of the fluid from the buffer storage tank and 50% of the fluid from the bypass line 99 is fed into line 95 via the valve 100 and, in particular, supplied to the heat consumer 92.

[0059] In Fig. Figure 2 shows the method 200 according to the invention. The individual process steps of method 200 can be interchanged in their order.

[0060] In a first process step 210, the temperature of the returning fluid is determined. In particular, this is done by calculation and / or measurement using the return temperature sensor 91. The temperature of the fluid in a line, in particular 97, 98, which is located after the heat consumer and before the buffer storage tank 10, is recorded.

[0061] In a further process step 220, the temperature of the fluid 2 in the buffer storage tank 10 is determined. The temperature is measured in particular by the first temperature sensor 30, the second temperature sensor 31 and / or the third temperature sensor 32. Preferably, in an optional process step 222, an average value is determined from the measured temperature values.

[0062] Preferably, the temperature is recorded in the area of ​​sampling point 101. According to Fig. 1. The third temperature sensor 32 would measure the temperature.

[0063] Preferably, the temperature is measured using only a single temperature sensor.

[0064] Preferably, the temperature is measured in the second preheating area 13. In particular, the temperature is measured by the third temperature sensor 32.

[0065] According to an advantageous embodiment, in process step 220 the temperature of the fluid flowing back to the heat generator 20 in line 62 is determined. In particular, the determination is carried out using the optional temperature sensor 51. Accordingly, in the subsequent process steps, the temperature of the fluid in line 62 is used instead of the temperature of the fluid in the buffer storage tank 10.

[0066] According to an advantageous embodiment, the temperature of the fluid in line 62 and the temperature in the buffer storage tank are recorded in process step 220. In process step 222, the values ​​are correlated with each other, in particular the average is calculated, and in particular the lower of the two values ​​is selected.

[0067] The process steps 210 and 220 can be arbitrarily interchanged in their order.

[0068] In a further process step 230, the determined temperature of fluid 2 in the buffer storage tank 10 is compared with the determined temperature of the returning fluid 2. In particular, a temperature difference is calculated. If the temperature difference exceeds a predetermined offset, the process continues with process step 240.

[0069] For example, if the temperature of the returning fluid is 38°C and the measured temperature of the fluid in the buffer tank is 35°C, the temperature difference is 3°C. With a given offset of 2°C, the process would continue with step 240. With a given offset of 4°C, steps 210 and 220 would be repeated, or the optional step 250 would be executed.

[0070] In process step 240, a control signal is provided. This control signal causes the valve 100 to be switched, in particular moved to the second switching position, such that the returning fluid 2 is at least partially, preferably substantially, diverted via the bypass 99 past the buffer storage tank 10 and back into the heating circuit 90. This prevents the fluid in the buffer storage tank 10 from being heated by the returning fluid 2. Particularly during thermal disinfection, the returning fluid 2 may be so hot that it leads to undesirable heating of the buffer storage tank. The fluid 2 is cooled by flowing through the heat consumer 92 again.

[0071] In process step 250, a control signal is provided. This control signal causes valve 100 to be switched, specifically moved to the first switching position, such that the returning fluid 2 is directed into the buffer storage tank 10. This occurs when the returning fluid is colder than the fluid in the buffer storage tank. Alternatively, the valve is switched in this manner when the temperature of the returning fluid 2 is below a predetermined value.

[0072] Furthermore, a hysteresis mechanism can be incorporated, which prevents fluctuations in temperature from causing the valve 100 to constantly switch between the first and second positions. In particular, a hysteresis value is specified for this purpose. Preferably, the hysteresis value is 4 degrees Celsius or 4 Kelvin.

[0073] According to an advantageous embodiment of the invention, the fluid flowing back from at least one heat consumer 92 is diverted at least partially through the bypass 99 depending on a further condition. This condition is as follows: If an outside temperature below a predetermined value, in particular below 0°C and / or frost, is detected, the fluid flowing back from at least one heat consumer 92, despite a temperature difference determined in process step 230, preferably greater than the predetermined offset, or an elevated temperature, is nevertheless not routed substantially all of the way through the bypass 99. One of the process steps 210 and 220 is repeated, or the optional process step 250 is executed. Process step 240 is not executed. In particular, this is a further condition for process step 230.

[0074] The returning fluid is directed at least partially, and in particular substantially completely, into the buffer storage tank 10. This leads to a heating of the fluid in the buffer storage tank 10. The heated fluid in the buffer storage tank 10 can be supplied to the heat generator 20, in particular via line 62, thereby heating and, if necessary, defrosting it. The thermal energy in the fluid returning to the heat generator 20 can be used for defrosting the heat generator.

[0075] Preferably, heat is supplied to the refrigeration circuit of the heat generator 20 via the heat exchanger. This heat can then be used, in particular, for heating, and especially defrosting, the other heat exchanger.

Claims

[1] Method (200) for operating a heating system (1) which has at least one first heat generator (20), in particular a heat pump, for heating a fluid (2) in a buffer storage tank (10), and wherein the heated fluid (4) circulates between the buffer storage tank (10) and at least one heat consumer (92) by means of a heating circuit (90), and wherein a bypass (99) is provided which allows the fluid (4) flowing back to the buffer storage tank (10) in the heating circuit (90) to be at least partially diverted past the buffer storage tank (10) and supplied to the at least one heat consumer (92) again, and wherein the temperature of the fluid (4) in the buffer storage tank (10) is determined (210), characterized by, that the temperature of the returning fluid is determined (220), and that the returning fluid is at least partially directed via the bypass (99) (230, 240) if the determined temperature of the returning fluid is warmer than a predetermined temperature, in particular the determined temperature of the fluid in the buffer storage (10). [2] Method (200) according to the preceding claim, characterized by , that the returning fluid is at least partially directed via the bypass (99) if the temperature difference between the determined temperature of the returning fluid and the determined temperature of the fluid (2) in the buffer storage (10) exceeds a predetermined offset. [3] Method (200) according to any one of the preceding claims, characterized by that a hysteresis is formed which has at least a predetermined hysteresis value. [4] Method (100) according to any one of the preceding claims, characterized by, that the temperature of the fluid in the buffer storage (10) is determined by the first temperature sensor (30) and / or second temperature sensor (31) and / or third temperature sensor (32) in the buffer storage (10). [5] Heating system (1) with a measuring and control device (3) which is configured to carry out all process steps of the method (200) according to any of the preceding claims. [6] Computer program that causes a measuring and control device (3) to perform all the process steps of the method (200) according to any one of claims 1 to 5 when executed on the measuring and control device (3). [7] Machine-readable storage medium with a computer program stored thereon according to claim 6.

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