Arrangement for a combined heat and power system

Abstract

Arrangement for a combined cooling and heating system with a refrigeration circuit and a heat pump circuit, which have a common intermediate pressure tank (7) and are thereby thermally connected to each other, wherein the refrigeration circuit also has at least one evaporator (3), a refrigeration compressor (1) and a throttle valve (5) and the heat pump circuit also has at least one heat pump compressor (2), a condenser (4) and a heat pump throttle valve (6), the intermediate pressure tank (7) has a sump area in its bottom region in which liquid refrigerant is located, the heat pump throttle valve (6) is arranged downstream of the condenser (4), wherein a controllable heat exchanger, the combined heat exchanger (11), which is communicatively connected to the intermediate pressure tank (7), is additionally arranged in the refrigeration circuit, and the combined heat exchanger (11) is thermally connected to an external heat sink and heat source for the purpose of heat input or output.wherein the combined heat exchanger (11) is communicatively connected to the intermediate pressure tank (7) such that an upper refrigerant-side channel section is connected to the vapor space of the intermediate pressure tank (7) and a lower refrigerant-side channel section is connected to the sump area of ​​the intermediate pressure tank (7) and a heat transfer fluid is present in the combined heat exchanger (11) between the inlet (111) and outlet (112).

Description

[0001] The invention relates to an arrangement for a cold-heat coupling with two counterclockwise cold vapor processes, the refrigeration cycle and the heat pump cycle, which are thermally connected.

[0002] The refrigeration cycle contains at least one evaporator, in which the refrigerant evaporates by absorbing a heat flow; a refrigeration compressor to increase the refrigerant pressure to an intermediate pressure level; and an expansion valve to reduce the refrigerant pressure to a low pressure level, resulting in liquid refrigerant and refrigerant flash vapor. The heat pump cycle contains at least one heat pump compressor to increase the refrigerant vapor pressure to a high pressure level; a condenser to transfer heat of heat from cooling and condensation to a heat transfer fluid; and a heat pump expansion valve to reduce the refrigerant pressure to an intermediate pressure level, resulting in liquid refrigerant and refrigerant flash vapor. The heat flow transferred to the heat transfer fluid is referred to as heating power.

[0003] Cooling capacity is the intended use of the refrigeration cycle. Heating capacity is the intended use of the heat pump cycle.

[0004] The refrigeration circuit and the heat pump circuit are thermally connected via a vessel, referred to here as the intermediate pressure tank, to transfer heat from the refrigeration circuit to the heat pump circuit. This allows a heat flow to be transferred from the refrigeration circuit to the heat pump circuit. The intermediate pressure tank contains liquid refrigerant in its bottom section, known as the sump section. This refrigerant, along with flash vapor, is generated after the system expands from high pressure to intermediate pressure in the heat pump's expansion valve. The heat pump's expansion valve is located downstream of the condenser.

[0005] The liquefied refrigerant from the sump area flows to the expansion valve of the refrigeration cycle, where it is expanded to low pressure directly into the evaporator or into a low-pressure separator that communicates with the evaporator. This process produces refrigerant liquid and refrigerant flash vapor. The refrigerant liquid is evaporated by the addition of heat, thus generating the cooling capacity. The evaporated refrigerant and flash vapor are extracted by the refrigerant compressor. The required cooling capacity influences the amount of vapor extracted.

[0006] In the intermediate pressure tank, the heat flow inherent in the compressed gas from the refrigeration compressor is transferred directly from the gaseous refrigerant to the liquid refrigerant in the sump area of ​​the tank via internal heat transfer. For this purpose, the compressed gas from the refrigeration compressor is introduced into the liquid refrigerant. The liquid refrigerant evaporates, and the introduced compressed gas from the refrigeration compressor is cooled back to a saturated vapor state. The total vapor volume, consisting of (a) refrigerant from the refrigeration compressor cooled back to a saturated vapor state, (b) medium-pressure flash vapor after expansion from the condenser, and (c) vapor generated by deheating, flows to the heat pump compressor in the heat pump cycle, is drawn in by the heat pump compressor, compressed to a high-pressure level, and then liquefied.

[0007] The heating output depends on the refrigerant mass flow through the refrigeration compressor and its outlet temperature.

[0008] Cooling capacity and heating capacity are in a fixed ratio to each other.

[0009] They cannot be independently adjusted to the respective cooling and heating requirements.

[0010] The described combined cooling and heating system can either adjust the cooling capacity to the cooling demand or the heating capacity to the heating demand, resulting in the other heat flow not being generated as required. If the cooling capacity is adjusted to the demand, there is either too much or too little heating capacity. Conversely, if the heating capacity is adjusted to the demand, there is either too much or too little cooling capacity.

[0011] Therefore, in most cases, combined heat and power (CHP) cannot be operated economically, even though it represents an ideal combination for cooling and heating.

[0012] Therefore, combined heat and power (CHP) systems often have to be implemented as bivalent systems in combination with auxiliary heating to achieve the required heating temperature level, or some of the heating output is released unused into the environment. This undesirably increases installation and / or operating costs and makes it more difficult to utilize the otherwise very effective CHP technology.

[0013] The object of the invention is to provide cooling and heating power as required by a new arrangement of a cooling-heat coupling with a refrigeration circuit and a heat pump circuit.

[0014] The arrangement of a combined heat and power system according to the invention has a refrigeration circuit and a heat pump circuit, in each of which refrigerant circulates, which changes its state of matter during circulation.

[0015] In addition to the components evaporator, refrigeration compressor, heat pump compressor, condenser, intermediate pressure tank and throttle valves, the combined heat and cooling system includes a controllable heat exchanger located downstream of the refrigeration compressor, which is to be referred to as a "combined heat exchanger".

[0016] The combined heat exchanger has separate channels through which the refrigerant of the heat pump circuit flows on one side and an external heat transfer fluid, such as water or air, flows on the other. The external heat transfer fluid is able to absorb heat in the combined heat exchanger when the temperature of the refrigerant in the intermediate pressure tank is higher than the temperature of the heat transfer fluid, or to release heat in the combined heat exchanger when the temperature of the refrigerant in the intermediate pressure tank is lower than the temperature of the heat transfer fluid.

[0017] In the refrigerant-side channel sections of the combined heat exchanger, refrigerant is heated and / or condensed or evaporated depending on the temperature difference. The combined heat exchanger is connected to the intermediate pressure tank in such a way that an upper refrigerant-side channel section is connected to the vapor space of the intermediate pressure tank and a lower refrigerant-side channel section is connected to the sump area of ​​the intermediate pressure tank.

[0018] Depending on the temperature of the refrigerant in the intermediate pressure tank relative to the external heat transfer fluid, heat is either removed or added. The temperature in the intermediate pressure tank is adjusted by the heat pump compressor in response to varying heating demands. If the heating demand increases, the flow rate of the heat pump compressor must increase. Consequently, the pressure in the intermediate pressure tank, and thus the evaporation temperature of the refrigerant in the sump area of ​​the intermediate pressure tank, drops below the temperature of the external heat transfer fluid. This allows heat from the external source to be transferred into the heat pump circuit via the external heat transfer fluid in the combined heat exchanger. The lower refrigerant-carrying sections of the combined heat exchanger, which communicate with the intermediate pressure tank, contain liquid refrigerant that evaporates as a result of the heat input.The steam enters the intermediate pressure tank via the refrigerant-side channel section located at the top of the combined heat exchanger, which communicates with the steam space of the intermediate pressure tank. From there, it is extracted by the heat pump compressor. The heating output subsequently increases.

[0019] If the heating demand decreases in this configuration, the flow rate of the heat pump compressor must be reduced. Consequently, the pressure in the intermediate pressure tank rises, and thus the evaporation temperature of the refrigerant in the sump area of ​​the intermediate pressure tank rises above the temperature of the external fluid. This allows the external heat transfer fluid to act as a cooling fluid, and heat can be dissipated from the heat pump circuit to the outside via the combined heat exchanger.

[0020] The vapor enters the combined heat exchanger via the upper refrigerant-side channel section, which communicates with the vapor space of the intermediate pressure tank, where it is liquefied by heat extraction. The lower refrigerant-carrying channel sections, which also communicate with the intermediate pressure tank, contain liquid refrigerant, which flows into the tank by gravity. Consequently, the heating capacity decreases.

[0021] The evaporation temperature in the sump area of ​​the intermediate pressure tank is below the temperature of the external heat transfer fluid when external heat is coupled in, while it is above the temperature of the external heat transfer fluid when heat is coupled out. Cooling tower water, process water, cooling water from other consumers or even air can be used as a heat source or heat sink.

[0022] The temperature levels of the heat source or heat sink determine the intermediate pressure level of the cooling-heat coupling, depending on the refrigerant.

[0023] Advantageous variants for the arrangement of the additional evaporator in a combined heat and power system are proposed in the exemplary embodiments.

[0024] The intermediate pressure affects the temperature in the intermediate pressure tank.

[0025] The solution according to the invention includes the use of the same fluid as a heat transfer medium and as a refrigerant.

[0026] The invention is explained using exemplary embodiments.

[0027] Fig. Figure 1 shows a known arrangement for a combined cooling and heating system with a refrigeration cycle and a heat pump cycle.

[0028] In Fig. 2, Fig. 3, Fig. 4 relate to arrangements according to the invention.

[0029] The combined heat and power system according to Fig. Figure 1 shows a first counterclockwise cold vapor process, the refrigeration cycle, and a second counterclockwise cold vapor process, the heat pump cycle, in which the same refrigerant circulates, changing its state of matter during circulation in the respective cycle.

[0030] The refrigeration circuit contains an evaporator. 3 , in which the refrigerant absorbs a heat flow – between the connections 31 , 32 – evaporates and thereby generates cooling power, a refrigeration compressor 1 to increase the pressure of the refrigerant to the intermediate pressure level in the intermediate pressure tank 7 and a throttle valve 5 to reduce the pressure of the refrigerant to a low-pressure level. This process produces refrigerant liquid and refrigerant flash vapor.

[0031] The heat pump compressor is part of the heat pump circuit. 2to increase the pressure of the refrigerant vapor to a high-pressure level, a condenser 4 for the liquefaction of the refrigerant and downstream after the condenser 4 a heat pump throttle valve 6 It is arranged to reduce the pressure of the refrigerant to the intermediate pressure level. The heat flow required for desuperheating and condensation is the heating power.

[0032] Cooling capacity is the intended use of the refrigeration cycle. Heating capacity is the intended use of the heat pump cycle.

[0033] The refrigeration circuit and heat pump circuit are connected via the intermediate pressure tank for heat transfer from the refrigeration circuit to the heat pump circuit. 7 thermally connected, so that a heat flow is transferred from the refrigeration cycle to the heat pump cycle.

[0034] The intermediate pressure tank 7Its bottom area, known as the sump area, contains liquid refrigerant, which, together with flash steam, is released after expansion from the high-pressure level in the heat pump throttle valve. 6 at intermediate pressure level at the connection 71 into the intermediate pressure tank 7 was supplied.

[0035] In the intermediate pressure tank 7 This will be done via the pressure line 74 The pressurized gas supplied to the refrigeration circuit is cooled down. For this purpose, the pressurized gas is directed into the sump area of ​​the intermediate pressure tank. 7 The refrigerant is introduced and deheated, causing the liquid refrigerant to evaporate. The heat is transferred directly from the gaseous refrigerant to the liquid refrigerant. The liquid refrigerant evaporates, and the pressurized gas introduced into the refrigerant compressor is cooled back to a saturated vapor state. The entire vapor volume then passes to the heat pump compressor. 2 , is compressed to high pressure and then in the condenser 4deheated and liquefied.

[0036] The liquid refrigerant from the sump area of ​​the intermediate pressure tank 7 , reaches the throttle valve 5 of the refrigeration circuit, where it connects to a low-pressure level at the connection 81 into the low-pressure separator 8 enters. The low-pressure separator 8 communicates with the evaporator 3 via inlet 82 and unspecified vapor channel. Refrigerant liquid evaporates as a result of heat input in the evaporator. 3 , so that the cooling capacity is generated as an equivalent. Evaporated refrigerant and flash steam are drawn in via the suction line. 83 from the refrigerant compressor 1 The air is extracted, compressed, and cooled back down to saturated steam in the intermediate pressure tank. The required cooling capacity influences the intake flow rate to the refrigeration compressor and thus also the flow rate from the heat pump compressor. 2It must be promoted.

[0037] Since this depends on the cooling capacity, the heating capacity cannot be adjusted as needed. The mass flow rate m KA to the refrigeration compressor 1 and m WP to the heat pump compressor 2 They depend on the cooling capacity. Their relationship to each other is fixed and cannot be arbitrarily changed. This is the disadvantage of conventional combined heat and power (CHP) systems.

[0038] Fig. Figure 2 shows an arrangement of a cold-heat coupling according to the invention.

[0039] In addition to the other components, the combined heat and power (CHP) system includes a refrigeration compressor. 1 , heat pump compressor 2 , low-pressure separator 8 , evaporator 3 liquefiers 4 , intermediate pressure tank 7 , throttle valve 5 and WP throttle valve 6 , a controllable heat exchanger, the combined heat exchanger 7, which is connected to the intermediate pressure tank 7 communicated.

[0040] In the combined heat exchanger 11 Heat is added to or removed from the combined heat and power (CHP) system as needed. This occurs in the combined heat exchanger. 11 There are separate channels that connect to the intermediate pressure tank on the one hand. 7 communicate and, on the other hand, are permeated by water.

[0041] In the refrigerant-side duct sections of the combined heat exchanger 11 Depending on the heating output requirements, refrigerant is heated and / or condensed or evaporated. The combined heat exchanger 11 is with the intermediate pressure tank 7 connected in such a way that a refrigerant-side channel section located at the top is connected to the vapor space of the intermediate pressure tank. 7 and a refrigerant-side channel section located below, with the sump area of ​​the intermediate pressure tank. 7 is connected.

[0042] Depending on the temperature of the refrigerant in the intermediate pressure tank 7 The temperature in the intermediate pressure tank depends on the suction pressure of the heat pump compressor. Heat is either transferred to the external cooling fluid or supplied by the external heating fluid. 7 The flow rate of the heat pump compressor is adjusted in response to varying heating demands. If the heating demand increases in this configuration, the flow rate of the heat pump compressor must be adjusted accordingly. 2 increase. The flow rate of the heat pump compressor. 2 The speed is increased, resulting in a decrease in pressure in the intermediate pressure tank. 7 and thus the evaporation temperature of the refrigerant in the sump area of ​​the intermediate pressure tank 7 below the temperature of the external fluid to such an extent that the external fluid in the combined heat exchanger 11Heat can be supplied from outside into the heat pump circuit. This occurs in the lower refrigerant-carrying sections of the combined heat exchanger. 11 , which is connected to the intermediate pressure tank 7 The system contains liquid refrigerant, which evaporates upon heat input. The vapor passes through the refrigerant-side channel section of the combined heat exchanger located at the top. 11 , which is connected to the steam space of the intermediate pressure tank 7 communicated, into the intermediate pressure tank 7 , from where it passes through the heat pump compressor 2 is sucked away.

[0043] The heating output increases as a result of the larger mass flow through the heat pump compressor.

[0044] If the heating demand decreases in this configuration, the flow rate of the heat pump compressor must be adjusted. 2 become smaller. The flow rate of the heat pump compressor. 2This is altered by a lower rotational speed. Consequently, the pressure in the intermediate pressure tank increases. 7 and thus the evaporation temperature of the refrigerant in the sump area of ​​the intermediate pressure tank 7 via the temperature of the external fluid, so that the external fluid acts as a cooling fluid and transfers heat to the outside in the combined heat exchanger 11 can be discharged from the heat pump circuit.

[0045] The steam passes through the refrigerant-side channel section of the combined heat exchanger located at the top. 11 , which is connected to the steam space of the intermediate pressure tank 7 communicated, into the combined heat exchanger 11 , where it is liquefied by heat extraction. In the lower refrigerant-carrying duct sections, which connect to the intermediate pressure tank. 7 To communicate, there is liquid refrigerant which, as a result of gravity, enters the intermediate pressure tank. 7 expires.

[0046] The heating output decreases as a result of the smaller mass flow through the heat pump compressor.

[0047] The evaporation temperature in the sump area of ​​the intermediate pressure tank 7 When external heat is coupled in, the temperature at the inlet is below that of the external fluid. 111 , whereas when heat is extracted from the external fluid, it lies above the temperature of the external fluid. The temperature difference between the inlet and the external fluid influences this. 111 and process 112 the required pressure in the intermediate pressure tank 7 , to couple heat in for higher heating demand or couple it out for lower heating demand.

[0048] Depending on the heating demand, the flow rate of the heat pump compressor is increased or decreased, so that heat is subsequently coupled in or coupled out.

[0049] Cooling tower water, process water, or cooling water from other consumers can be used as the heating fluid in the described arrangements.

[0050] Fig. Figure 3 shows an arrangement of a combined heat and power (CHP) system, as in Fig. 2 shown. The outside air according to Fig. The third component is used as a heat source or heat sink, depending on demand. A refrigerant whose phase changes upon heating and cooling is advantageously used as the heat transfer fluid.

[0051] The external heat exchanger 109 Depending on temperature and humidity, it is operated with water spray as an evaporation condenser or dry without water spray.

[0052] If heat is to be extracted, the external heat exchanger is used. 109It is operated with water spray. At an outside air temperature of 32°C and a relative humidity of 60%, the wet-bulb temperature is approximately 21°C. The heat can be dissipated to the outside at approximately 32°C by condensing the heat transfer fluid.

[0053] If heat is to be coupled in, the heat exchanger is used. 109 It operates at an ambient air temperature of, for example, 32°C in "dry" mode without water spray. The outside air is drawn into the heat exchanger. 109 For example, it is cooled by 10 K so that heat can be coupled in at approximately 20°C. The evaporation temperature in the intermediate pressure tank is adjusted as a result of the heating demand by varying the intake volume flow of the heat pump compressor. 2 adapted so that heat can be extracted or coupled in.

[0054] Fig.Figure 4 shows a combined heat and power (CHP) system where outside air is used as a heat source or heat sink. The refrigerant-to-air heat exchanger 110 communicates via the fluid line 14 and steam line 15 with the intermediate pressure tank 7 This eliminates the need for additional temperature differences between the external heat transfer fluid and the evaporation temperature in the intermediate pressure tank for heat transfer into and out of the combined heat and power (CHP) system.

[0055] The refrigerant combination heat exchanger 110 It is sprinkled with water depending on temperature and humidity. 103 operated as an evaporative condenser, so that the heat sink has wet-bulb temperature, or operated without water spray, so that the heat sink or the heat source has ambient air temperature.

[0056] The refrigerant circulation pump is used for transporting refrigerant to couple heat from the environment. 12 in operation while the return valve 13 The system is closed. The refrigerant circulation pump draws liquid refrigerant from the sump of the intermediate pressure tank. 7 into the refrigerant combination heat exchanger 110 , where the refrigerant evaporates. The water spray. 103 is out of service.

[0057] The refrigerant circulation pump is used to extract heat from the environment. 12 out of service while the return valve 13 while it is open.

[0058] Refrigerant vapor enters via the steam line 15 into the refrigerant combination heat exchanger 110 , is liquefied there and flows through liquid pipes 14 and return valve 13 into the sump area of ​​the intermediate pressure tank 7 The water sprinkler 103is out of service. The fan speed 104 is adjusted depending on the load.

[0059] The described arrangements according to the invention allow the heating output in a combined heat and power system to be controlled independently of the cooling output under changing operating conditions. Reference symbol list 1 refrigeration compressor 2 heat pump compressors 3 evaporators 4 liquefiers 5 Throttle valve 6 WP throttle valve 7 Intermediate pressure tank 8 low-pressure separators 11 Combined heat exchangers 12 Refrigerant circulation pump 13 Return valve 14 Liquid line 15 Steam pipe 31 connection 32 connection 41 connection 42 connection 71 connection 72 Liquid drainage 73 Suction line 74 Pressure line 81 connection 82 Inflow 83 Suction line 103 Water sprinkler 104 fans 109 Heat exchangers 110 Refrigerant combination heat exchangers 111 Inflow 112 Expiry

Claims

[1] Arrangement for a combined cooling and heating system with a refrigeration circuit and a heat pump circuit, which share a common intermediate pressure tank ( 7 ) possess and are thus thermally connected to each other, with the refrigeration cycle also including at least one evaporator ( 3 ), a refrigeration compressor ( 1 ) and a throttle valve ( 5 ) and the heat pump circuit also includes at least one heat pump compressor ( 2 ), a liquefier ( 4 ) and a heat pump throttle valve ( 6 ) possess, the intermediate pressure tank ( 7 ) has a sump area in its base containing liquid refrigerant, the WP throttle valve ( 6 ) downstream of the condenser ( 4 ) is arranged, characterized by that the refrigeration circuit also includes a controllable heat exchanger, the combined heat exchanger ( 11 ), which is connected to the intermediate pressure tank ( 7) is connected in a communicating manner, is arranged, and the combined heat exchanger ( 11 ) is thermally connected to an external heat sink and heat source for the purpose of heat input or output. [2] Arrangement for a combined heat and cooling system according to claim 1, characterized by that the combined heat exchanger ( 11 ) with the intermediate pressure tank ( 7 ) is connected in such a way that a refrigerant-side channel section located at the top is connected to the vapor space of the intermediate pressure tank ( 7 ) and a refrigerant-side channel section located below, with the sump area of ​​the intermediate pressure tank ( 7 ) is connected and in the combined heat exchanger ( 11 ) between inflow ( 111 ) and process ( 112 ) a heat transfer fluid is present. [3] Arrangement for a combined cooling and heating system with a refrigeration circuit and with a heat pump circuit according to claims 1 and 2, characterized by that the combined heat exchanger ( 11 ) via inflow (111 ) and process ( 112 ) with a heat exchanger ( 109 ) is connected, which has at least one fan and at least one adjustable water sprinkler and is located in the combined heat exchanger ( 11 ), in the heat exchanger ( 109 ), inflow ( 111 ) and process ( 112 ) a common volatile heat transfer fluid with temperature-dependent phase change is present. [4] Arrangement for a combined cooling and heating system with a refrigeration circuit and with a heat pump circuit according to claim 3, characterized by that in the intermediate pressure tank ( 7 ), in the combined heat exchanger ( 11 ), in the heat exchanger ( 109 ), inflow ( 111 ) and process ( 112 ) the refrigerant for the combined heat and power (CHP) system is present.

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