A cascade heat pump unit

Abstract

The utility model discloses a cascade heat pump unit, including a low-level refrigerant circulation unit, a first heat exchange unit, a high-level refrigerant circulation unit, a second heat exchange unit, a low-temperature hot water delivery unit and a high-temperature hot water delivery unit. The first heat exchange unit includes a first heat exchange shell, and the first heat exchange shell is provided with a first heat exchange channel A, a first heat exchange channel B and a first heat exchange channel C. The first heat exchange channel A is connected to the low-level refrigerant circulation unit, the first heat exchange channel B is connected to the high-level refrigerant circulation unit, and the first heat exchange channel C is connected to the low-temperature hot water delivery unit. The utility model adopts the cascade heating principle, uses two independent systems of high and low temperature for cascade heating, and generates a high-temperature heat source of 120°C; at the same time, a single-stage independently operated low-level refrigerant circulation unit is used to obtain a low-temperature heat source. This device can obtain heat sources of different temperatures according to specific needs, providing a wider application space for industrial heating.

Description

Technical Field

[0001] The utility model belongs to the technical field of heating equipment, and specifically relates to a cascade heat pump unit. Background Art

[0002] Many industries in the industry need to use heating equipment, such as heating boilers, heat pump air conditioning units, etc. As China's traditional coal-fired boilers for heating, they not only have low energy utilization, but also cause serious pollution to the atmosphere. Therefore, coal-fired boilers are being gradually eliminated in some cities. The use of oil and gas boilers has high operating costs. The use of electric heating consumes a lot of electricity, is less efficient, and is more expensive. The use of traditional air source heat pump air conditioning units for heat pump heating will be affected by the low ambient temperature in winter. Below -5℃, the unit will be unstable and the heating capacity will decrease, making it difficult to meet user requirements. Water source heat pump is an alternative solution to heating and air conditioning that has great advantages both technically and economically. The current maximum water outlet temperature of water source heat pump units is 55°C (such as R22 refrigerant) or 65°C (such as R134a refrigerant). Its working pressure is too high under high temperature conditions, the compression ratio is large, and the energy efficiency ratio is low. It is difficult to obtain hot water above 85°C. In addition, it is limited by the operating limit of the compressor. The safety and reliability of the unit in long-term operation under high temperature conditions is low, and it cannot provide sufficiently stable hot water. Utility Model Content

[0003] The purpose of the utility model is to provide a cascade heat pump unit to solve the above problems existing in the prior art.

[0004] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a cascade heat pump unit, including a low-level refrigerant circulation unit, a first heat exchange unit, a high-level refrigerant circulation unit, a second heat exchange unit, a low-temperature hot water delivery unit and a high-temperature hot water delivery unit, the first heat exchange unit includes a first heat exchange shell, the first heat exchange shell is provided with a first heat exchange channel A, a first heat exchange channel B and a first heat exchange channel C that can exchange heat with each other, the first heat exchange channel A is connected to the low-level refrigerant circulation unit, the first heat exchange channel B is connected to the high-level refrigerant circulation unit, and the first heat exchange channel C is connected to the low-temperature hot water delivery unit; the second heat exchange unit includes a second heat exchange shell, the second heat exchange shell is provided with a second heat exchange channel A and a second heat exchange channel B that can exchange heat with each other, the second heat exchange channel A is connected to the high-level refrigerant circulation unit, and the second heat exchange channel B is connected to the high-temperature hot water delivery unit.

[0005] As an optional implementation of the above technical solution, the low-temperature hot water delivery unit includes a low-temperature hot water tank, a low-temperature hot water pipe A and a low-temperature hot water pipe B. The low-temperature hot water tank is equipped with a low-temperature hot water output device. The low-temperature hot water pipe A, the first heat exchange channel C and the low-temperature hot water pipe B are connected in sequence. The end of the low-temperature hot water pipe A away from the first heat exchange channel C is connected to the low-temperature hot water tank, and the end of the low-temperature hot water pipe B away from the first heat exchange channel C is connected to the low-temperature hot water tank. A low-temperature hot water pump is provided on the low-temperature hot water pipe A or the low-temperature hot water pipe B.

[0006] As an optional implementation of the above technical solution, the low-temperature hot water output device includes an input pipe and an output pipe, the input pipe is connected to the low-temperature hot water pipe A, and the output pipe is connected to the low-temperature hot water pipe B.

[0007] As an optional implementation of the above technical solution, a waste heat recovery device is provided inside the low-temperature hot water tank, and the waste heat recovery device includes a low-temperature water inlet pipe, a low-temperature heat exchange pipe and a low-temperature drain pipe. The low-temperature water inlet pipe, the low-temperature heat exchange pipe and the low-temperature drain pipe are connected in sequence, and the low-temperature heat exchange pipe is arranged in the low-temperature hot water tank.

[0008] As an optional implementation of the above technical solution, a first heat exchange tube A and a first heat exchange tube B that can exchange heat with each other are provided inside the first heat exchange shell, and the first heat exchange tube A and the first heat exchange tube B are both arranged in the first heat exchange channel C, the first heat exchange channel A is arranged inside the first heat exchange tube A, and the first heat exchange channel B is arranged inside the first heat exchange tube B.

[0009] As an optional implementation of the above technical solution, the low-temperature hot water tank is provided with a first water supply pipe and a first pressure gauge.

[0010] As an optional implementation of the above technical solution, the high-temperature hot water delivery unit includes a high-temperature hot water tank, a high-temperature hot water pipe A and a high-temperature hot water pipe B. The high-temperature hot water tank is connected to a high-temperature hot water output device. The high-temperature hot water pipe A, the second heat exchange channel C and the high-temperature hot water pipe B are connected in sequence. The end of the high-temperature hot water pipe A away from the second heat exchange channel C is connected to the high-temperature hot water tank, and the end of the high-temperature hot water pipe B away from the second heat exchange channel C is connected to the high-temperature hot water tank. A high-temperature hot water pump is provided on the high-temperature hot water pipe A or the high-temperature hot water pipe B.

[0011] As an optional implementation of the above technical solution, the high-temperature hot water output device includes a high-temperature drain pipe and a return pipe, one end of the high-temperature drain pipe and the return pipe are connected to the high-temperature hot water tank, and the other end of the high-temperature drain pipe and the return pipe are connected to the water-using equipment.

[0012] As an optional implementation of the above technical solution, the high-temperature hot water tank is provided with a second water supply pipe, a second pressure gauge, a steam exhaust pipe and a safety valve.

[0013] As an optional implementation of the above technical solution, a second heat exchange tube is provided inside the second heat exchange shell, a second heat exchange channel A is provided inside the second heat exchange tube, and the second heat exchange tube is provided in the second heat exchange channel B.

[0014] As an optional implementation of the above technical solution, the low-level refrigerant circulation unit includes a low-level compressor, a low-level four-way valve, a bridge valve assembly, a low-level liquid storage tank, a low-level drying filter, a low-level plate heat exchanger, a low-level main electromagnetic expansion valve, a low-level auxiliary electromagnetic expansion valve, a low-level fin heat exchanger and a low-level gas-liquid separator, and the low-level compressor, the low-level four-way valve, the first heat exchange channel A, the bridge valve assembly, the low-level liquid storage tank, the low-level drying filter, and the low-level plate heat exchanger are connected in sequence. It is connected to the input end of the bridge valve assembly, the output end of the bridge valve assembly is connected to the low-level fin heat exchanger, the low-level fin heat exchanger is connected to the low-level four-way valve, one end of the low-level gas-liquid separator is connected to the low-level compressor, the other end of the low-level gas-liquid separator is connected to the low-level four-way valve, the low-level plate heat exchanger is used to exchange heat for the low-level compressor, a low-level auxiliary electromagnetic expansion valve is provided between the low-level drying filter and the low-level plate heat exchanger, and a low-level main electromagnetic expansion valve is provided between the low-level plate heat exchanger and the bridge valve assembly.

[0015] As an optional implementation of the above technical solution, the refrigerant of the low-stage refrigerant circulation unit is R410a.

[0016] As an optional implementation of the above technical solution, the advanced refrigerant circulation unit includes an advanced compressor, an advanced liquid storage tank, an advanced drying filter, an advanced plate heat exchanger, an advanced main electromagnetic expansion valve, an advanced auxiliary electromagnetic expansion valve and an advanced gas-liquid separator. The advanced compressor, the second heat exchange channel A, the advanced liquid storage tank, the advanced drying filter, the advanced plate heat exchanger, the advanced main electromagnetic expansion valve, the first heat exchange channel B and the advanced gas-liquid separator are connected in sequence. The advanced plate heat exchanger is used to exchange heat for the advanced compressor. An advanced auxiliary electromagnetic expansion valve is provided between the advanced drying filter and the advanced plate heat exchanger.

[0017] As an optional implementation of the above technical solution, the refrigerant of the advanced refrigerant circulation unit is R234fa.

[0018] The beneficial effects of the utility model are:

[0019] The utility model provides a cascade heat pump unit, which adopts the cascade heating principle, combines a low-level refrigerant circulation unit with a high-level refrigerant circulation unit, and uses two independent high and low temperature systems for cascade heating to generate a high-temperature heat source of 120°C; at the same time, a single-stage independently operated low-level refrigerant circulation unit is used to obtain a low-temperature heat source. This device can obtain heat sources of different temperatures according to specific needs, providing a wider application space for industrial heating. The utility model avoids the use of coal-fired boilers, reduces possible pollution to the environment, and fully utilizes the energy-saving advantages of heat pumps to obtain a higher temperature heat source from a low-temperature environment, with higher heating efficiency and more obvious economic advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of an implementation method of the utility model.

[0021] In the figure: 1-first heat exchange shell; 2-first heat exchange channel C; 3-second heat exchange shell; 4-second heat exchange channel B; 5-low-temperature hot water tank; 6-low-temperature hot water pipe A; 7-low-temperature hot water pipe B; 8-low-temperature hot water pump; 9-input pipe; 10-output pipe; 11-waste heat recovery device; 12-first heat exchange pipe A; 13-first heat exchange pipe B; 14-high-temperature hot water tank; 15-high-temperature hot water pipe A; 16-high-temperature hot water pipe B; 17-high-temperature hot water pump; 18-high-temperature drain pipe; 19-return pipe; 20-second heat exchange pipe; 2 1- low-level compressor; 22- low-level four-way valve; 23- bridge valve assembly; 24- low-level liquid storage tank; 25- low-level drier filter; 26- low-level plate heat exchanger; 27- low-level main electromagnetic expansion valve; 28- low-level auxiliary electromagnetic expansion valve; 29- low-level fin heat exchanger; 30- low-level gas-liquid separator; 31- high-level compressor; 32- high-level liquid storage tank; 33- high-level drier filter; 34- high-level plate heat exchanger; 35- high-level main electromagnetic expansion valve; 36- high-level auxiliary electromagnetic expansion valve; 37- high-level gas-liquid separator. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, this embodiment provides a cascade heat pump unit, including a low-level refrigerant circulation unit, a first heat exchange unit, a high-level refrigerant circulation unit, a second heat exchange unit, a low-temperature hot water delivery unit and a high-temperature hot water delivery unit, wherein the first heat exchange unit is arranged between the low-level refrigerant circulation unit and the high-level refrigerant circulation unit, and the low-temperature hot water delivery unit can exchange heat with the low-level refrigerant circulation unit and the high-level refrigerant circulation unit, so that the low-temperature hot water delivery unit can output low-temperature hot water. The second heat exchange unit is arranged between the high-level refrigerant circulation unit and the high-temperature hot water delivery unit, and the high-temperature hot water delivery unit can exchange heat with the high-level refrigerant circulation unit, so that the high-temperature hot water delivery unit can output high-temperature hot water.

[0023] The first heat exchange unit includes a first heat exchange shell 1, in which a first heat exchange channel A, a first heat exchange channel B and a first heat exchange channel C2 capable of mutual heat exchange are arranged, the first heat exchange channel A is connected to a low-level refrigerant circulation unit, the first heat exchange channel B is connected to a high-level refrigerant circulation unit, and the first heat exchange channel C2 is connected to a low-temperature hot water delivery unit. The second heat exchange unit includes a second heat exchange shell 3, in which a second heat exchange channel A and a second heat exchange channel B4 capable of mutual heat exchange are arranged, the second heat exchange channel A is connected to a high-level refrigerant circulation unit, and the second heat exchange channel B4 is connected to a high-temperature hot water delivery unit. The first heat exchange unit uses three media for heat exchange to achieve multifunctional operation of the system.

[0024] The utility model provides a cascade heat pump unit, which adopts the cascade heating principle, combines a low-level refrigerant circulation unit with a high-level refrigerant circulation unit, and uses two independent high and low temperature systems for cascade heating to generate a high-temperature heat source of 120°C; at the same time, a single-stage independently operated low-level refrigerant circulation unit is used to obtain a low-temperature heat source. This device can obtain heat sources of different temperatures according to specific needs, providing a wider application space for industrial heating. The utility model avoids the use of coal-fired boilers, reduces possible pollution to the environment, and fully utilizes the energy-saving advantages of heat pumps to obtain a higher temperature heat source from a low-temperature environment, with higher heating efficiency and more obvious economic advantages.

[0025] In this embodiment, the low-temperature hot water delivery unit includes a low-temperature hot water tank 5, a low-temperature hot water pipe A6 and a low-temperature hot water pipe B7. The low-temperature hot water tank 5 is equipped with a low-temperature hot water output device. The low-temperature hot water tank 5 is provided with a first water supply pipe and a first pressure gauge. The low-temperature hot water pipe A6, the first heat exchange channel C2 and the low-temperature hot water pipe B7 are connected in sequence. The end of the low-temperature hot water pipe A6 away from the first heat exchange channel C2 is connected to the low-temperature hot water tank 5, and the end of the low-temperature hot water pipe B7 away from the first heat exchange channel C2 is connected to the low-temperature hot water tank 5. A low-temperature hot water pump 8 is provided on the low-temperature hot water pipe A6 or the low-temperature hot water pipe B7. The low-temperature hot water pump 8 drives water to circulate between the low-temperature hot water tank 5 and the low-level refrigerant circulation unit to obtain low-temperature hot water.

[0026] The first heat exchange shell 1 is provided with a first heat exchange tube A12 and a first heat exchange tube B13 capable of mutual heat exchange. The first heat exchange tube A12 and the first heat exchange tube B13 are both arranged in the first heat exchange channel C2. The first heat exchange tube A12 is provided with the first heat exchange channel A, and the first heat exchange tube B13 is provided with the first heat exchange channel B. Low-temperature refrigerant and high-temperature refrigerant flow through the first heat exchange tube A12 and the first heat exchange tube B13, respectively, and water flows through the first heat exchange shell 1, which can not only recover external heat energy higher than the low-temperature heat source, but also transfer heat energy lower than the low-temperature heat source to the outside.

[0027] The low-temperature hot water output device includes an input pipe 9 and an output pipe 10, wherein the input pipe 9 is connected to the low-temperature hot water pipe A6, and the output pipe 10 is connected to the low-temperature hot water pipe B7. The cold water of the input pipe 9 enters the first heat exchange channel C2 through the low-temperature hot water pipe A6, and the cold water absorbs the heat of the first heat exchange channel A and enters the output pipe 10 through the low-temperature hot water pipe B7, thereby obtaining low-temperature hot water. A waste heat recovery device 11 is provided inside the low-temperature hot water tank 5, and the waste heat recovery device 11 includes a low-temperature water inlet pipe, a low-temperature heat exchange pipe and a low-temperature drain pipe, wherein the low-temperature water inlet pipe, the low-temperature heat exchange pipe and the low-temperature drain pipe are connected in sequence, and the low-temperature heat exchange pipe is arranged in the low-temperature hot water tank 5, and the water in the low-temperature hot water tank 5 is recovered by the low-temperature heat exchange pipe. The low-temperature heat exchange pipe is placed in the low-temperature hot water tank 5, and can absorb the waste heat of the high-level refrigerant circulation unit or other heat sources to reduce the low-pressure stage operating power and achieve energy saving.

[0028] In this embodiment, the high temperature hot water delivery unit includes a high temperature hot water tank 14, a high temperature hot water pipe A15 and a high temperature hot water pipe B16. The high temperature hot water tank 14 is connected to a high temperature hot water output device. The high temperature hot water tank 14 is provided with a second water supply pipe, a second pressure gauge, a steam discharge pipe and a safety valve. The high temperature hot water pipe A15, the second heat exchange channel C and the high temperature hot water pipe B16 are connected in sequence. The end of the high temperature hot water pipe A15 away from the second heat exchange channel C is connected to the high temperature hot water tank 14. The end of the high temperature hot water pipe B16 away from the second heat exchange channel C is connected to the high temperature hot water tank 14. A high temperature hot water pump 17 is provided on the high temperature hot water pipe A15 or the high temperature hot water pipe B16. Water flows in the heat exchange coil and refrigerant flows between the shell and tube to improve the heat exchange efficiency. The high temperature hot water pump 17 drives water to circulate between the high temperature hot water tank 14 and the high temperature hot water delivery unit, thereby obtaining high temperature hot water. A second heat exchange tube 20 is disposed inside the second heat exchange shell 3 , a second heat exchange channel A is disposed inside the second heat exchange tube 20 , and the second heat exchange tube 20 is disposed in the second heat exchange channel B4 .

[0029] Among them, the high-temperature hot water output device includes a high-temperature drain pipe 18 and a return pipe 19, one end of the high-temperature drain pipe 18 and the return pipe 19 are connected to the high-temperature hot water tank 14, and the other ends of the high-temperature drain pipe 18 and the return pipe 19 are connected to the water-using equipment. The high-temperature hot water is stored in the high-temperature hot water tank 14, and the high-temperature hot water is transported to the water-using equipment through the high-temperature drain pipe 18. The water used by the water-using equipment is transported to the high-temperature hot water tank 14 through the return pipe 19 to realize water recycling.

[0030] In one embodiment, the low-level refrigerant circulation unit includes a low-level compressor 21, a low-level four-way valve 22, a bridge valve assembly 23, a low-level liquid storage tank 24, a low-level drying filter 25, a low-level plate heat exchanger 26, a low-level main electromagnetic expansion valve 27, a low-level auxiliary electromagnetic expansion valve 28, a low-level fin heat exchanger 29 and a low-level gas-liquid separator 30, wherein the low-level compressor 21, the low-level four-way valve 22, the first heat exchange channel A, the bridge valve assembly 23, the low-level liquid storage tank 24, the low-level drying filter 25, and the low-level plate heat exchanger 26 are connected in sequence, and the low-level plate heat exchanger and the bridge valve assembly are connected in sequence. The input end of the bridge valve assembly 23 is connected, the output end of the bridge valve assembly 23 is connected to the low-level fin heat exchanger 29, the low-level fin heat exchanger 29 is connected to the low-level four-way valve 22, one end of the low-level gas-liquid separator 30 is connected to the low-level compressor 21, and the other end of the low-level gas-liquid separator 30 is connected to the low-level four-way valve 22. The low-level plate heat exchanger 26 is used to exchange heat with the low-level compressor 21. A low-level auxiliary electromagnetic expansion valve 28 is provided between the low-level filter drier 25 and the low-level plate heat exchanger 26, and a low-level main electromagnetic expansion valve 27 is provided between the low-level plate heat exchanger 26 and the bridge valve assembly 23. The refrigerant of the low-level refrigerant circulation unit is R410a.

[0031] In the low-stage compressor 21, the refrigerant is selected to have a wide evaporation temperature range and a relatively low condensation temperature, such as R134a, R410a, etc. In order to adapt to the wide evaporation temperature, the low-stage compressor 21 selects steam injection to increase heat enthalpy, and the motor adopts a variable frequency type. Since a variable frequency compressor is used, the low-stage four-way valve 22 adopts a variable frequency four-way valve to ensure normal switching at low frequency or low evaporation temperature. The low-stage plate heat exchanger 26 plays an intermediate cooling role, and provides steam injection to increase heat enthalpy for the low-stage compressor 21 when the ambient temperature is low. The bridge valve assembly 23 is used to switch the liquid flow direction, and the low-stage fin heat exchanger 29 contains a forced circulation fan for heat absorption and heat release on the air side. The low-stage gas-liquid separator 30 is used to separate the liquid refrigerant to prevent liquid accumulation in the low-stage compressor 21.

[0032] In one embodiment, the advanced refrigerant circulation unit includes an advanced compressor 31, an advanced liquid storage tank 32, an advanced filter dryer 33, an advanced plate heat exchanger 34, an advanced main electromagnetic expansion valve 35, an advanced auxiliary electromagnetic expansion valve 36 and an advanced gas-liquid separator 37. The advanced compressor 31, the second heat exchange channel A, the advanced liquid storage tank 32, the advanced filter dryer 33, the advanced plate heat exchanger 34, the advanced main electromagnetic expansion valve 35, the first heat exchange channel B and the advanced gas-liquid separator 37 are connected in sequence. The advanced plate heat exchanger 34 is used to exchange heat with the advanced compressor 31. A high-level auxiliary electromagnetic expansion valve 36 is provided between the advanced filter dryer 33 and the advanced plate heat exchanger 34. The refrigerant of the advanced refrigerant circulation unit is R234fa.

[0033] The high-level compressor 31 uses a fixed frequency. Since a high exhaust temperature is generated at a low evaporation temperature, a steam injection enthalpy increase type compressor is selected, and a refrigerant with a high saturated condensation temperature is selected, such as R515B, R245fa, R1234yf, etc. The high-level plate heat exchanger 34 plays an intermediate cooling role, providing steam injection enthalpy increase for the high-level compressor 31 at a low evaporation temperature, so as to reduce the exhaust temperature of the high-level compressor 31, reduce the pressure ratio, and improve the heating efficiency.

[0034] The utility model utilizes R410a refrigerant single-stage compression, and can obtain a heat source below 60°C from an environment of -7°C to -25°C. By utilizing R234fa refrigerant with an evaporation temperature within the range of 20°C to 75°C, a saturated condensation temperature of 135°C can be obtained, thereby obtaining a heat source of 120°C. Through two refrigerants, the cascade refrigeration principle is adopted, and cascade refrigeration of two independent high and low temperature systems is utilized to generate a high-temperature heat source. At the same time, waste heat is fully utilized, and waste heat after the 120°C heat source is utilized is recovered to reduce the energy consumption of the low-temperature heat pump unit; at the same time, a low-temperature heat source is obtained by single-stage independent operation, and a high-temperature heat source is obtained by dual-machine cascade operation. This device can obtain heat sources of different temperatures according to demand, providing a wider application space for dual-machine cascade heating.

[0035] The operation mode of the cascade heat pump unit of the utility model is described as follows:

[0036] 1. Single-machine operation mode: When the single machine is in operation, it is limited to the low-level refrigerant circulation unit, and can realize single cooling and single heating modes.

[0037] a: The refrigerant flow direction of the single-machine refrigeration process is: the first heat exchange pipe A12 → the low-level four-way valve e port → the low-level four-way valve g port → the low-level gas-liquid separator 30 → the low-level compressor 21 → the low-level four-way valve f port → the low-level four-way valve h port → the low-level fin heat exchanger 29 (the low-level fin heat exchanger 29 exchanges heat with the atmosphere, i.e., dissipates heat) → the bridge valve assembly D port → the bridge valve assembly C port → the low-level liquid storage tank 24 → the low-level drying filter 25 → the low-level plate heat exchanger 26 → the low-level main electromagnetic expansion valve 27 → the bridge valve assembly a port → the bridge valve assembly b port → the first heat exchange pipe A12, forming a refrigeration cycle. At this time, the circulating water of the low-temperature hot water pump 8 forms an external cooling system after heat exchange through the first heat exchange channel A. The system automatically controls the start and stop, frequency increase or frequency reduction of the low-level compressor 21 according to the water temperature change in the first heat exchange channel A.

[0038] The refrigerant flow direction of the single-machine heating process is: low-level fin heat exchanger 29 → low-level four-way valve h port → low-level four-way valve g port → low-level gas-liquid separator 30 → low-level compressor 21 → low-level four-way valve f port → low-level four-way valve e port → first heat exchange tube A12 → bridge valve assembly b port → bridge valve assembly c port → low-level liquid storage tank 24 → low-level drying filter 25 → low-level plate heat exchanger 26 → low-level main electromagnetic expansion valve 27 → bridge valve assembly a port → bridge valve assembly D port → low-level fin heat exchanger 29. When the ambient temperature is higher than -3°C, the low-stage auxiliary electromagnetic expansion valve 28 is closed. When the ambient temperature is lower than -3°C, the low-stage auxiliary electromagnetic expansion valve 28 controls the opening degree through PID regulation to provide a steam injection enthalpy increase function for the low-stage compressor 21, thereby reducing the exhaust temperature of the low-stage compressor 21 and increasing the heating capacity of the low-stage compressor 21. During heating, the circulating water of the low-temperature hot water pump 8 is converted into hot water after heat exchange through the first heat exchange channel A, providing a low-temperature heat source (40-45°C) for the load.

[0039] 2. Cascade coupling heating: both the low-level refrigerant circulation unit and the high-level refrigerant circulation unit are in operation.

[0040] The working mode of the cascade coupling heating is: first, the heating mode of the low-level refrigerant circulation unit is turned on. The working cycle is consistent with the single heating process (including temperature control and steam injection enthalpy increase mode), but the conditions for limiting the opening of the high-level are different. Only when the medium temperature in the first heat exchange tube A12 is higher than the set value (the adjustable range of this set value is 25℃-45℃), for example, 45℃, the high-level compressor 31 starts to work. When the temperature in the second heat exchange tube 20 is lower than 30℃, the compressor steam injection enthalpy increase system works, and the high-level compressor 31 reduces the exhaust temperature and reduces the pressure ratio, so as to achieve energy saving and increase the heating capacity. At this time, the refrigerant of the high-level refrigerant circulation unit flows to: high-level gas-liquid separator 37→high-level compressor 31→second heat exchange tube 20→high-level liquid storage tank 32→high-level filter drier 33→high-level plate heat exchanger 34→high-level main electromagnetic expansion valve 35→first heat exchange tube B13→high-level gas-liquid separator 37, and circulates. At this time, the low-temperature hot water pump 8 is working, the electric butterfly valves of the input pipe 9 and the output pipe 10 are closed, and the waste heat recovery device 11 can control whether waste heat recovery is needed according to the waste heat temperature. When the actual temperature in the low-temperature hot water tank 5 is more than 5°C higher than the preset temperature, the waste heat recovery device 11 can be put into operation; the high-temperature hot water delivery unit passes the high-temperature hot water or hot steam to the high-temperature hot water tank 14 through the high-temperature hot water pump 17, and provides heat source to the outside through the high-temperature drain pipe 18. The excess medium-temperature heat source in the low-temperature hot water tank 5 is recovered by the waste heat recovery device 11.

[0041] The utility model can achieve high-temperature hot water and steam (90°C - 120°C) through this cascade coupling operation mode, and through overall experiments, the comprehensive energy efficiency reaches more than 1.9 in winter, and the energy efficiency is about 2.5-2.7 in summer. Compared with other combustion boiler rooms that produce the same calorific value, the operating cost is lower. At the same time, this solution provides a new operation mode for one machine with multiple uses, and is a device worthy of development.

[0042] In the description of the present utility model, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, and may be fixedly connected, detachably connected, or integrated; may be mechanically connected or electrically connected; may be directly connected or indirectly connected through an intermediate medium, may be the internal connection of two components or the interaction relationship between two components. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood. In addition, the specific features, structures, etc. described in the embodiments are included in at least one embodiment. In the absence of mutual contradictions, those skilled in the art may combine the features of different embodiments. The scope of protection of the present utility model is not limited to the above-mentioned specific embodiments. According to the basic technical concept of the present utility model, the embodiments that can be associated with by ordinary technicians in this field without creative work all belong to the scope of protection of the present utility model.

Claims

1. A cascade heat pump unit, characterized in that: The invention comprises a low-stage refrigerant circulation unit, a first heat exchange unit, a high-stage refrigerant circulation unit, a second heat exchange unit, a low-temperature hot water delivery unit and a high-temperature hot water delivery unit. The first heat exchange unit comprises a first heat exchange shell (1). The first heat exchange shell (1) is provided with a first heat exchange channel A, a first heat exchange channel B and a first heat exchange channel C (2) capable of mutually exchanging heat. The first heat exchange channel A is connected to the low-stage refrigerant circulation unit, the first heat exchange channel B is connected to the high-stage refrigerant circulation unit, and the first heat exchange channel C (2) is connected to the low-temperature hot water delivery unit. The second heat exchange unit comprises a second heat exchange shell (3). The second heat exchange shell (3) is provided with a second heat exchange channel A and a second heat exchange channel B (4) capable of mutually exchanging heat. The second heat exchange channel A is connected to the high-stage refrigerant circulation unit, and the second heat exchange channel B (4) is connected to the high-temperature hot water delivery unit.

2. The cascade heat pump unit according to claim 1, characterized in that: The low-temperature hot water delivery unit comprises a low-temperature hot water tank (5), a low-temperature hot water pipe A (6) and a low-temperature hot water pipe B (7); the low-temperature hot water tank (5) is provided with a low-temperature hot water output device; the low-temperature hot water pipe A (6), the first heat exchange channel C (2) and the low-temperature hot water pipe B (7) are connected in sequence; the end of the low-temperature hot water pipe A (6) away from the first heat exchange channel C (2) is connected to the low-temperature hot water tank (5); the end of the low-temperature hot water pipe B (7) away from the first heat exchange channel C (2) is connected to the low-temperature hot water tank (5); and a low-temperature hot water pump (8) is provided on the low-temperature hot water pipe A (6) or the low-temperature hot water pipe B (7).

3. The cascade heat pump unit according to claim 2, characterized in that: The low-temperature hot water output device comprises an input pipe (9) and an output pipe (10), wherein the input pipe (9) is connected to the low-temperature hot water pipe A (6), and the output pipe (10) is connected to the low-temperature hot water pipe B (7).

4. The cascade heat pump unit according to claim 2, characterized in that: A waste heat recovery device (11) is provided inside the low-temperature hot water tank (5), and the waste heat recovery device (11) comprises a low-temperature water inlet pipe, a low-temperature heat exchange pipe and a low-temperature drain pipe, wherein the low-temperature water inlet pipe, the low-temperature heat exchange pipe and the low-temperature drain pipe are connected in sequence, and the low-temperature heat exchange pipe is arranged in the low-temperature hot water tank (5).

5. The cascade heat pump unit according to claim 3, characterized in that: The first heat exchange shell (1) is provided with a first heat exchange tube A (12) and a first heat exchange tube B (13) capable of exchanging heat with each other. The first heat exchange tube A (12) and the first heat exchange tube B (13) are both arranged in a first heat exchange channel C (2). The first heat exchange channel A is arranged inside the first heat exchange tube A (12), and the first heat exchange channel B is arranged inside the first heat exchange tube B (13). The low-temperature hot water tank (5) is provided with a first water supply pipe and a first pressure gauge.

6. The cascade heat pump unit according to claim 1, characterized in that: The high-temperature hot water delivery unit comprises a high-temperature hot water tank (14), a high-temperature hot water pipe A (15) and a high-temperature hot water pipe B (16); the high-temperature hot water tank (14) is connected to a high-temperature hot water output device; the high-temperature hot water pipe A (15), the second heat exchange channel C and the high-temperature hot water pipe B (16) are connected in sequence; the end of the high-temperature hot water pipe A (15) away from the second heat exchange channel C is connected to the high-temperature hot water tank (14); the end of the high-temperature hot water pipe B (16) away from the second heat exchange channel C is connected to the high-temperature hot water tank (14); and a high-temperature hot water pump (17) is provided on the high-temperature hot water pipe A (15) or the high-temperature hot water pipe B (16).

7. The cascade heat pump unit according to claim 6, characterized in that: The high-temperature hot water output device comprises a high-temperature drain pipe (18) and a return pipe (19), one end of each of the high-temperature drain pipe (18) and the return pipe (19) is connected to the high-temperature hot water tank (14), and the other end of each of the high-temperature drain pipe (18) and the return pipe (19) is connected to a water-using device.

8. The cascade heat pump unit according to claim 6, characterized in that: The high-temperature hot water tank (14) is provided with a second water supply pipe, a second pressure gauge, a steam exhaust pipe and a safety valve; a second heat exchange tube (20) is provided inside the second heat exchange shell (3), a second heat exchange channel A is provided inside the second heat exchange tube (20), and the second heat exchange tube (20) is provided in the second heat exchange channel B (4).

9. The cascade heat pump unit according to claim 5, characterized in that: The low-stage refrigerant circulation unit comprises a low-stage compressor (21), a low-stage four-way valve (22), a bridge valve assembly (23), a low-stage liquid storage tank (24), a low-stage drying filter (25), a low-stage plate heat exchanger (26), a low-stage main electromagnetic expansion valve (27), a low-stage auxiliary electromagnetic expansion valve (28), a low-stage fin heat exchanger (29) and a low-stage gas-liquid separator (30). The low-stage compressor (21), the low-stage four-way valve (22), the first heat exchange channel A, the bridge valve assembly (23), the low-stage liquid storage tank (24), the low-stage drying filter (25) and the low-stage plate heat exchanger (26) are connected in sequence. The low-stage plate heat exchanger is connected to the input end of the bridge valve assembly (23). The bridge valve assembly The output end of (23) is connected to the low-level fin heat exchanger (29), the low-level fin heat exchanger (29) is connected to the low-level four-way valve (22), one end of the low-level gas-liquid separator (30) is connected to the low-level compressor (21), and the other end of the low-level gas-liquid separator (30) is connected to the low-level four-way valve (22), the low-level plate heat exchanger (26) is used to exchange heat with the low-level compressor (21), a low-level auxiliary electromagnetic expansion valve (28) is provided between the low-level drying filter (25) and the low-level plate heat exchanger (26), and a low-level main electromagnetic expansion valve (27) is provided between the low-level plate heat exchanger (26) and the bridge valve assembly (23); the refrigerant of the low-level refrigerant circulation unit is R410a.

10. The cascade heat pump unit according to claim 9, characterized in that: The high-level refrigerant circulation unit comprises a high-level compressor (31), a high-level liquid storage tank (32), a high-level drying filter (33), a high-level plate heat exchanger (34), a high-level main electromagnetic expansion valve (35), a high-level auxiliary electromagnetic expansion valve (36) and a high-level gas-liquid separator (37); the high-level compressor (31), the second heat exchange channel A, the high-level liquid storage tank (32), the high-level drying filter (33), the high-level plate heat exchanger (34), the high-level main electromagnetic expansion valve (35), the first heat exchange channel B and the high-level gas-liquid separator (37) are connected in sequence; the high-level plate heat exchanger (34) is used to perform heat exchange on the high-level compressor (31); a high-level auxiliary electromagnetic expansion valve (36) is provided between the high-level drying filter (33) and the high-level plate heat exchanger (34); the refrigerant of the high-level refrigerant circulation unit is R234fa.

Images