阅读说明：本技术 一种燃气热泵空调热回收系统及其控制方法 (Gas heat pump air conditioner heat recovery system and control method thereof ) 是由 张建鹏 冯自平 于 2021-01-14 设计创作，主要内容包括：本发明公开一种燃气热泵空调热回收系统及其控制方法,包括烟气排放系统、冷媒系统、冷却水系统和生活热水系统；烟气排放系统包括依次连接的燃气发动机的排气端、第一烟气换热器的热介质通道、消声器、第二烟气换热器的热介质通道以及后处理设备,第二烟气换热器的冷介质通道与生活热水系统的管线连接；冷却水系统用于收集燃气发动机的缸套的余热,缸套的水输出端与第一烟气换热器的冷介质通道连接；冷媒系统包括与燃气发动机的动力输出端连接的压缩机,压缩机的冷媒输出端与第二热回收器的热介质通道连接。本发明通过优化发动机余热回收的分配方式,提高热回收率,提高热回收系统稳定性以及减少控制单元频繁切换,解决了冷却水温度波动剧烈的问题。(The invention discloses a gas heat pump air-conditioning heat recovery system and a control method thereof, wherein the gas heat pump air-conditioning heat recovery system comprises a flue gas discharge system, a refrigerant system, a cooling water system and a domestic hot water system; the smoke discharge system comprises an exhaust end of the gas engine, a heat medium channel of the first smoke heat exchanger, a silencer, a heat medium channel of the second smoke heat exchanger and post-treatment equipment which are connected in sequence, and a cold medium channel of the second smoke heat exchanger is connected with a pipeline of the domestic hot water system; the cooling water system is used for collecting waste heat of a cylinder sleeve of the gas engine, and a water output end of the cylinder sleeve is connected with a cooling medium channel of the first flue gas heat exchanger; the refrigerant system comprises a compressor connected with the power output end of the gas engine, and the refrigerant output end of the compressor is connected with the heat medium channel of the second heat recoverer. According to the invention, by optimizing the distribution mode of the engine waste heat recovery, the heat recovery rate is improved, the stability of the heat recovery system is improved, the frequent switching of the control units is reduced, and the problem of severe fluctuation of the cooling water temperature is solved.)

1. A gas heat pump air conditioner heat recovery system is characterized by comprising a flue gas discharge system, a refrigerant system, a cooling water system and a domestic hot water system;

the smoke discharge system comprises an exhaust end of a gas engine, a heat medium channel of a first smoke heat exchanger, a silencer, a heat medium channel of a second smoke heat exchanger and post-treatment equipment which are connected in sequence, wherein a cold medium channel of the second smoke heat exchanger is connected with any section of pipeline of the domestic hot water system;

the cooling water system is used for collecting waste heat of a cylinder sleeve of the gas engine and waste heat of primary flue gas, and a water output end of the cylinder sleeve is connected with a cold medium channel of the first flue gas heat exchanger;

the refrigerant system comprises a compressor connected with the power output end of the gas engine, the refrigerant output end of the compressor is connected with a heat medium channel of a second heat recoverer, a cold medium channel of the second heat recoverer is connected with any section of pipeline of the domestic hot water system, a first heat recoverer is arranged in front of the evaporator input end of the refrigerant system and is connected with the heat medium channel of the first heat recoverer, and the cold medium channel of the first heat recoverer is connected with the pipeline of the cooling water system.

2. The gas heat pump air-conditioning heat recovery system of claim 1, wherein the cooling water system further comprises a first water pump, an output end of the first water pump is connected with a water input end of the cylinder sleeve, a cold medium channel of the first flue gas heat exchanger is respectively connected with a buffer water tank and a first electromagnetic valve through parallel branches, an output end of the buffer water tank is respectively connected with a first branch, a second branch and a third branch, the first branch comprises a third electromagnetic valve, an water outlet end of the third electromagnetic valve is connected with the cold medium channel of the first heat recoverer, the second branch comprises a second electromagnetic valve, an water outlet end of the second electromagnetic valve is connected with an outdoor radiator, the third branch comprises a fourth electromagnetic valve, an water outlet end of the fourth electromagnetic valve is connected with the hot medium channel of the third heat recoverer, and the cold medium channel of the third heat recoverer is connected with any section of the pipeline of the air-conditioning system, the output ends of the first branch, the second branch and the third branch are connected to the same node in parallel, and are connected with the input end of the first water pump through a first filter.

3. A gas heat pump air conditioner heat recovery system as set forth in claim 2, wherein the domestic hot water system comprises an output end of the second water pump, a cold medium passage of the second flue gas heat exchanger, a cold medium passage of the second heat recoverer, a domestic hot water tank, a second filter and an input end of the second water pump, which are connected in sequence.

4. A gas heat pump air conditioner heat recovery system as set forth in claim 3, wherein a temperature sensor T1 is provided in said surge tank, a temperature sensor T2 is provided at the outlet of the heat medium passage of said first flue gas heat exchanger, and a temperature sensor T3 is provided in said domestic hot water tank.

5. A gas heat pump air conditioner heat recovery system as set forth in claim 3, wherein said third solenoid valve is eliminated and said first heat recoverer is disposed in front of said surge tank.

6. A heat recovery control method for a gas heat pump air conditioner is characterized by being used for the gas heat pump air conditioner heat recovery system as claimed in claim 4, and comprising a refrigerating and heating mode, a first heating mode, a second heating mode and a third heating mode, wherein the refrigerating and heating mode is used for refrigerating or high-temperature heating of multiple units, the heat exchange capacity of the first heat recoverer and the heat exchange capacity of the outdoor radiator are judged according to the heat exchange capacity of refrigerating circulation, when the first heat recoverer and the outdoor radiator are respectively used as evaporators of a cooling water system, if the heat exchange capacity of the first heat recoverer is higher than that of the outdoor radiator, the first heating mode is selected, otherwise, the second heating mode is selected, the first heating recoverer is used for heating of the multiple units or a cold and hot water unit without starting the third heat recoverer at low ambient temperature, the second heating mode is used for conventional heating of the cold and hot water unit, and the third heating mode is used for adding the first heat recoverer as cooling water on the basis of the first heating mode The water system evaporator is used for starting the cold and hot water machine of the third heat recoverer to heat at low ambient temperature;

the refrigeration and heating mode comprises the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the second electromagnetic valve are opened, and the third electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the first electromagnetic valve and the second electromagnetic valve are opened, the third electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of a fan of the outdoor radiator is increased; when T2min + delta T1 is not less than T1 and is less than T2max, the first electromagnetic valve and the second electromagnetic valve are opened, the third electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, stopping the gas engine;

the first heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the third electromagnetic valve are opened, and the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the third electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min + Δ T1 is less than or equal to T1< T2min + Δ T2, the second electromagnetic valve and the third electromagnetic valve are opened, and the first electromagnetic valve and the fourth electromagnetic valve are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve and the third electromagnetic valve are opened, the first electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of a fan of the outdoor radiator is increased; when T2 max-delta T3 is not less than T1< T2max, the second electromagnetic valve and the third electromagnetic valve are opened, the first electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, stopping the gas engine;

the second heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the fourth electromagnetic valve are opened, and the second electromagnetic valve and the third electromagnetic valve are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the fourth electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the third electromagnetic valve are closed; when T2min + Δ T1 is less than or equal to T1< T2min + Δ T2, the second electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve and the third electromagnetic valve are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve and the third electromagnetic valve are closed, and meanwhile, the rotating speed of a fan of the outdoor radiator is increased; when T2 max-delta T3 is not less than T1< T2max, the second electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve and the third electromagnetic valve are closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, stopping the gas engine;

the third heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the third electromagnetic valve are opened, and the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the third electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min + Δ T1 is less than or equal to T1< T2min + Δ T2, the third electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve and the second electromagnetic valve are closed; when T2min + Δ T2 is less than or equal to T1< T2max- Δ T3, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve is closed; when T2 max-delta T3 is not less than T1 and is less than T2 max-delta T4, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve is closed, and meanwhile, the rotating speed of a fan of the outdoor radiator is increased; when T2 max-delta T4 is not less than T1< T2max, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve is closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, stopping the gas engine;

wherein Δ T1, Δ T2, Δ T3 and Δ T4 are design temperature differences; t1min is the lowest temperature for cooling water recovery; t2min is the minimum recovery temperature T1min of the cooling water plus a preset temperature difference of a heat exchanger; t2max is the cooling water overheat protection temperature.

Technical Field

The invention relates to the field of gas-driven air source heat pump air conditioners, in particular to a gas heat pump air conditioner heat recovery system and a control method thereof.

Background

The gas heat pump adopts a gas engine to drive a refrigerant compressor to operate so as to realize a vapor compression refrigeration cycle. One important reason for the high efficiency of the gas heat pump air conditioner is that the waste heat can be recycled, and the engine waste heat can be divided into engine cylinder sleeve waste heat and waste gas waste heat. And the optimized control of the waste heat utilization mode of the gas heat pump not only can effectively improve the overall thermal performance of the unit, but also is the key for ensuring the safe and stable operation of the engine. However, the traditional waste heat utilization has the following problems:

1) at present, the flue gas heat recovery of an air source gas heat pump is unreasonable, the flue gas is once utilized and is reduced to condensation, a large heat exchange area is needed, and the cost is too high; if the heat is not directly discharged after being condensed, the heat recovery is insufficient, and the energy waste is caused;

2) at present, a thermostat is adopted in an air source gas heat pump waste heat recovery cooling water system to control the flow direction of water, the control is unstable, the temperature fluctuation of cooling water is severe, and the reliability of the system is reduced due to frequent switching of related control units.

Disclosure of Invention

Aiming at the problems, the invention provides a gas heat pump air-conditioning heat recovery system and a control method thereof, which mainly solve the problems of unreasonable flue gas heat recovery of an air source gas heat pump, severe fluctuation of cooling water temperature and frequent switching of a control unit.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the invention provides a gas heat pump air conditioning heat recovery system on the one hand, which comprises a flue gas discharge system, a refrigerant system, a cooling water system and a domestic hot water system;

the smoke discharge system comprises an exhaust end of the gas engine, a heat medium channel of the first smoke heat exchanger, a silencer, a heat medium channel of the second smoke heat exchanger and post-treatment equipment which are connected in sequence, and a cold medium channel of the second smoke heat exchanger is connected with any section of pipeline of the domestic hot water system;

the cooling water system is used for collecting the waste heat of a cylinder sleeve of the gas engine and the waste heat of primary flue gas, and the water output end of the cylinder sleeve is connected with a cold medium channel of the first flue gas heat exchanger;

the refrigerant system comprises a compressor connected with the power output end of the gas engine, the refrigerant output end of the compressor is connected with a heat medium channel of a second heat recoverer, a cold medium channel of the second heat recoverer is connected with any section of pipeline of the domestic hot water system, a first heat recoverer is arranged in front of the evaporator input end of the refrigerant system and is connected with the heat medium channel of the first heat recoverer, and the cold medium channel of the first heat recoverer is connected with the pipeline of the cooling water system.

In some embodiments, the cooling water system further includes a first water pump, an output end of the first water pump is connected to a water input end of the cylinder sleeve, a cold medium channel of the first flue gas heat exchanger is connected to the buffer water tank and the first electromagnetic valve through parallel branches, an output end of the buffer water tank is connected to the first branch, the second branch and the third branch, the first branch includes a third electromagnetic valve, a water outlet end of the third electromagnetic valve is connected to a cold medium channel of the first heat recoverer, the second branch includes a second electromagnetic valve, a water outlet end of the second electromagnetic valve is connected to the outdoor radiator, the third branch includes a fourth electromagnetic valve, a water outlet end of the fourth electromagnetic valve is connected to a hot medium channel of the third heat recoverer, a cold medium channel of the third heat recoverer is connected to any section of the air conditioning system through a pipeline, and output ends of the first branch, the second branch and the third branch are connected to the same node in parallel, and is connected with the input end of the first water pump through the first filter.

In some embodiments, the domestic hot water system comprises an output end of a second water pump, a cold medium channel of a second flue gas heat exchanger, a cold medium channel of a second heat recoverer, a domestic hot water tank, a second filter and an input end of the second water pump which are connected in sequence.

In some embodiments, a temperature sensor T1 is arranged in the buffer water tank, a temperature sensor T2 is arranged at the outlet of the heat medium channel of the first flue gas heat exchanger, and a temperature sensor T3 is arranged in the domestic hot water tank.

The invention also provides a heat recovery control method for the gas heat pump air-conditioner, which is used for the heat recovery system for the gas heat pump air-conditioner and comprises a refrigeration and heating mode, a first heating mode, a second heating mode and a third heating mode, wherein the refrigeration and heating mode is used for refrigeration or high-temperature heating of multi-connected machines, the heat exchange capacity of the first heat recoverer and an outdoor radiator which are respectively used as evaporators of a cooling water system is judged according to the heat exchange capacity of a refrigeration cycle, if the heat exchange capacity of the first heat recoverer is stronger than that of the outdoor radiator, the first heating mode is selected, otherwise, the second heating mode is selected, the first heating mode is used for heating of the multi-connected machine system or a cold and hot water unit without starting the third heat at low ambient temperature, the second heating mode is used for conventional heating of the cold and hot water unit, the third heating mode is additionally provided with the first heat recoverer on the basis of the first heating mode as an evaporator of the cooling water system, the cold and hot water machine for starting the third heat recoverer heats at low ambient temperature;

the refrigeration and heating mode comprises the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the second electromagnetic valve are opened, and the third electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the first electromagnetic valve and the second electromagnetic valve are opened, the third electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of a fan of the outdoor radiator is increased; when T2min + delta T1 is not less than T1 and is less than T2max, the first electromagnetic valve and the second electromagnetic valve are opened, the third electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine is stopped;

the first heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the third electromagnetic valve are opened, and the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and is less than T2min + delta T1, the third electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the fourth electromagnetic valve are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the second electromagnetic valve and the third electromagnetic valve are opened, and the first electromagnetic valve and the fourth electromagnetic valve are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve and the third electromagnetic valve are opened, the first electromagnetic valve and the fourth electromagnetic valve are closed, and meanwhile, the rotating speed of the fan of the outdoor radiator is increased; when T2 max-delta T3 is not less than T1 and T2max, the second electromagnetic valve and the third electromagnetic valve are opened, the first electromagnetic valve and the fourth electromagnetic valve are closed, and the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine is stopped;

the second heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the fourth electromagnetic valve are opened, and the second electromagnetic valve and the third electromagnetic valve are closed; when T2min is less than or equal to T1 and is less than T2min + delta T1, the fourth electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the third electromagnetic valve are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the second electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve and the third electromagnetic valve are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve and the third electromagnetic valve are closed, and meanwhile, the rotating speed of the fan of the outdoor radiator is increased; when T2 max-delta T3 is not less than T1 and T2max, the second electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve and the third electromagnetic valve are closed, and the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine is stopped;

the third heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve and the third electromagnetic valve are opened, and the second electromagnetic valve and the fourth electromagnetic valve are closed; when T2min is less than or equal to T1 and is less than T2min + delta T1, the third electromagnetic valve is opened, and the first electromagnetic valve, the second electromagnetic valve and the fourth electromagnetic valve are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the third electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve and the second electromagnetic valve are closed; when T1 is more than or equal to T2min + delta T2 and less than or equal to T2 max-delta T3, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, and the first electromagnetic valve is closed; when T2 max-delta T3 is not more than T1 and T2 max-delta T4, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve is closed, and meanwhile, the rotating speed of the fan of the outdoor radiator is increased; when T2 max-delta T4 is not less than T1 and T2max, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are opened, the first electromagnetic valve is closed, and meanwhile, the rotating speed of the gas engine is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine is stopped;

wherein Δ T1, Δ T2, Δ T3 and Δ T4 are design temperature differences; t1min is the lowest temperature for cooling water recovery; t2min is the minimum recovery temperature T1min of the cooling water plus a preset temperature difference of a heat exchanger; t2max is the cooling water overheat protection temperature.

The invention has the beneficial effects that: according to the invention, by optimizing the distribution mode of the waste heat recovery of the engine, the waste heat of the flue gas is utilized for the second time, meanwhile, the exhaust heat recovery of the compressor is increased, the heat recovery rate is improved, and the heat recovery of the system can reach 100% to the maximum; in addition, the cooling water system is controlled by an electromagnetic valve, a buffer water tank and a temperature sensor are additionally arranged, the stability of the heat recovery system is improved, frequent switching of a control unit is reduced, and the problem of severe temperature fluctuation of cooling water is solved.

Drawings

FIG. 1 is a schematic diagram of a gas heat pump air conditioning heat recovery system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a gas heat pump air conditioning heat recovery system disclosed in the second embodiment of the present invention;

wherein: 1-a gas engine, 2-a first flue gas heat exchanger, 3-a silencer, 4-a second flue gas heat exchanger, 5-a post-treatment device, 6-a cylinder sleeve, 7-a compressor, 8-a second heat recoverer, 9-a first heat recoverer, 10-a first water pump, 11-a buffer water tank, 12-a first electromagnetic valve, 13-a third electromagnetic valve, 14-a second electromagnetic valve, 15-an outdoor radiator, 16-a fourth electromagnetic valve, 17-a third heat recoverer, 18-a first filter, 19-a second water pump, 20-a domestic hot water tank and 21-a second filter.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the following detailed description of the present invention is provided with reference to the accompanying drawings and detailed description. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the relevant aspects of the present invention are shown in the drawings.

Example one

As shown in fig. 1, the embodiment provides a gas heat pump air conditioning heat recovery system, which includes a flue gas discharge system, a refrigerant system, a cooling water system and a domestic hot water system;

the smoke discharge system comprises an exhaust end of the gas engine 1, a heat medium channel of the first smoke heat exchanger 2, a silencer 3, a heat medium channel of the second smoke heat exchanger 4 and post-processing equipment 5 which are connected in sequence, and a cold medium channel of the second smoke heat exchanger 4 is connected with any section of pipeline of the domestic hot water system;

the cooling water system is used for collecting the waste heat of the cylinder sleeve 6 of the gas engine 1 and the waste heat of the primary flue gas, and the water output end of the cylinder sleeve 6 is connected with the cold medium channel of the first flue gas heat exchanger 2;

the refrigerant system comprises a compressor 7 connected with the power output end of the gas engine 1, the refrigerant output end of the compressor 7 is connected with a heat medium channel of a second heat recoverer 8, a cold medium channel of the second heat recoverer 8 is connected with any section of pipeline of the domestic hot water system, a first heat recoverer 9 is arranged in front of the evaporator input end of the refrigerant system and is connected with the heat medium channel of the first heat recoverer 9, and the cold medium channel of the first heat recoverer 9 is connected with the pipeline of the cooling water system.

The first flue gas heat exchanger 2 is used for recovering high-temperature flue gas heat discharged by the gas engine 1 to a cooling water system, and can cool flue gas at 300-600 ℃ to about 100 ℃. The second flue gas heat exchanger 4 is used for recovering the flue gas heat which is still at a higher temperature after being cooled by the first flue gas heat exchanger 2 to a domestic hot water system, and generally can reduce the flue gas temperature to about 60 ℃. The first heat recovery device 9 assists the evaporator to evaporate when the system pressure is lower, so that the side pressure of the system suction side is increased; the first heat recoverer 9 is also used in the system to replace a fin heat exchanger as an evaporator at low ring temperature (-10 ℃ and below), and the problem of low-temperature heating capacity attenuation of an air source heat pump is solved. The second heat recovery unit 8 is mainly used for recovering heat of the refrigerant system, and is generally disposed at an exhaust side of the compressor 7 of the refrigerant system to absorb heat of the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 7 for heating liquid in the domestic hot water tank 20.

According to the invention, by optimizing the distribution mode of waste heat recovery of the gas engine, the waste heat of the flue gas is utilized for the second time, meanwhile, the exhaust heat recovery of the compressor 7 is increased, the heat recovery rate is improved, and the heat recovery of the system can reach 100% at most; in addition, the cooling water system is controlled by an electromagnetic valve, a buffer water tank 11 and a temperature sensor are additionally arranged, the stability of the heat recovery system is improved, frequent switching of control units is reduced, and the problem of severe temperature fluctuation of cooling water is solved.

As one of the preferable embodiments of the present invention, the cooling water system further includes a first water pump 10, an output end of the first water pump 10 is connected with a water input end of the cylinder liner 6, a cold medium channel of the first flue gas heat exchanger 2 is respectively connected with the buffer water tank 11 and the first electromagnetic valve 12 through parallel branches, an output end of the buffer water tank 11 is respectively connected with a first branch, a second branch and a third branch, the first branch includes a third electromagnetic valve 13, a water outlet end of the third electromagnetic valve 13 is connected with a cold medium channel of the first heat recoverer 9, the second branch includes a second electromagnetic valve 14, a water outlet end of the second electromagnetic valve 14 is connected with an outdoor radiator 15, the third branch includes a fourth electromagnetic valve 16, a water outlet end of the fourth electromagnetic valve 16 is connected with a hot medium channel of the third heat recoverer 17, the cold medium channel of the third heat recoverer 17 is connected with any section of the pipeline of the air conditioning system, the output ends of the first, second and third branches are connected in parallel to the same node and are connected to the input end of the first water pump 10 through the first filter 18. The third heat recovery device 17 is a device belonging to an air conditioning system (cold and hot water unit), and is used for transferring heat absorbed by the cylinder sleeve 6 of the gas engine 1 and the first flue gas heat exchanger 2 to the cooling water system to the air conditioning system.

As one of the preferred embodiments of the present invention, the domestic hot water system comprises an output end of the second water pump 19, a cold medium channel of the second flue gas heat exchanger 4, a cold medium channel of the second heat recoverer 8, a domestic hot water tank 20, a second filter 21 and an input end of the second water pump 19 which are connected in sequence.

Furthermore, a temperature sensor T1 is arranged in the buffer water tank 11, a temperature sensor T2 is arranged at the outlet of the heat medium channel of the first flue gas heat exchanger 2, and a temperature sensor T3 is arranged in the domestic hot water tank 20.

The heat exchanger and the heat recoverer are generally arranged at the output end of the water pump, so that the advantage that the pressure of the output end is relatively high is facilitated, and the heat exchange efficiency of the main machine is improved.

Example two

As shown in fig. 2, in the first embodiment, the third solenoid valve 13 may be eliminated and the first heat recovery unit 9 may be disposed in front of the buffer tank due to structural design limitations or cost considerations.

EXAMPLE III

A heat recovery control method of a gas heat pump air conditioner is used for a gas heat pump air conditioner heat recovery system in the first embodiment and comprises a refrigerating and heating mode, a first heating mode, a second heating mode and a third heating mode, wherein the refrigerating and heating mode is used for refrigerating or high-temperature heating of multiple online machines, the heat exchange capacity of the first heat recoverer 9 and the heat exchange capacity of an outdoor radiator 15 which are respectively used as evaporators of a cooling water system are judged according to the heat exchange capacity of refrigerating circulation, if the heat exchange capacity of the first heat recoverer 9 is stronger than that of the outdoor radiator 15, the first heating mode is selected, otherwise, the second heating mode is selected, the first heating mode is used for heating of the multiple online machines or a cold and hot water unit without starting the third heat recoverer 17 at low ambient temperature, the second heating mode is used for conventional heating of the cold and hot water unit, the third heating mode is additionally provided with the first heat recoverer 9 as an evaporator of the cooling water system on the basis of the first heating mode, the cold and hot water machine for starting the third heat recoverer 17 heats at low ambient temperature; the heat exchange quantity is mainly calculated through some related parameters, and the related parameters refer to parameters of the refrigeration industry, such as suction pressure, discharge pressure, suction temperature, discharge temperature, heat exchange area and the like, of the refrigeration cycle of the air conditioner, so that the heat exchange quantity of the refrigeration cycle is calculated, and the parameters change under different working conditions and the heat exchange quantity also changes at any time. In the invention, the first heat recoverer 9 is a water-cooling heat exchanger but has a small heat exchange area, and the outdoor radiator 15 is an air-cooling heat exchanger but has a large heat exchange area.

The refrigeration and heating mode comprises the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve 12 and the second electromagnetic valve 14 are opened, and the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the first electromagnetic valve 12 and the second electromagnetic valve 14 are opened, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are closed, and meanwhile, the fan rotating speed of the outdoor radiator 15 is increased; when T2min + Δ T1 is not less than T1< T2max, the first electromagnetic valve 12 and the second electromagnetic valve 14 are opened, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are closed, and the rotating speed of the gas engine 1 is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine 1 is stopped; as shown in table 1 below. After the engine is started, the temperature of cooling water needs to be raised to a proper temperature as soon as possible, at the moment, the first electromagnetic valve 12 is opened, the second electromagnetic valve 14, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are closed, the first flue gas heat exchanger 2 cools the engine flue gas and simultaneously recovers waste heat to the cooling water system, and the temperature of the cooling water is gradually raised. When the outlet temperature T2 of the first flue gas heat exchanger 2 is detected to be more than or equal to Tmin, the control is different according to the mode selected by the unit: the first heat recoverer 9 or the third heat recoverer 17 in the cooling mode or the heating mode does not satisfy the working condition (at the moment, the heat of the cooling water system belongs to low-value heat to the air conditioning system, and the common situation is the cooling mode and the high-temperature heating mode of multi-connected air conditioner.)

TABLE 1 refrigeration and heating mode control logic

The first heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve 12 and the third electromagnetic valve 13 are opened, and the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the third electromagnetic valve 13 is opened, and the first electromagnetic valve 12, the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the second electromagnetic valve 14 and the third electromagnetic valve 13 are opened, and the first electromagnetic valve 12 and the fourth electromagnetic valve 16 are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve 14 and the third electromagnetic valve 13 are opened, the first electromagnetic valve 12 and the fourth electromagnetic valve 16 are closed, and meanwhile, the rotating speed of the fan of the outdoor radiator 15 is increased; when T2 max-delta T3 is not less than T1 and T2max, the second electromagnetic valve 14 and the third electromagnetic valve 13 are opened, the first electromagnetic valve 12 and the fourth electromagnetic valve 14 are closed, and the rotating speed of the gas engine 1 is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine 1 is stopped;

as shown in table 2 below. When the related parameters judge that the heat exchange capacity of the system is stronger than that of the outdoor radiator 15 when the first heat recoverer 9 is used as an evaporator, the system generally appears at low ambient temperature, such as minus 10 ℃ and below, and the system is suitable for a multi-split system and a cold and hot water machine without a third heat recoverer 17.

TABLE 2 first heating mode control logic

The second heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve 12 and the fourth electromagnetic valve 16 are opened, and the second electromagnetic valve 14 and the third electromagnetic valve 13 are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the fourth electromagnetic valve 16 is opened, and the first electromagnetic valve 12, the second electromagnetic valve 14 and the third electromagnetic valve 13 are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are opened, and the first electromagnetic valve 12 and the third electromagnetic valve 13 are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are opened, the first electromagnetic valve 12 and the third electromagnetic valve 13 are closed, and meanwhile, the rotating speed of the fan of the outdoor radiator 15 is increased; when T2 max-delta T3 is not less than T1 and T2max, the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are opened, the first electromagnetic valve 12 and the third electromagnetic valve 13 are closed, and the rotating speed of the gas engine 1 is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine 1 is stopped;

as shown in table 3 below. The method is suitable for conventional heating of a cold and hot water unit, namely, the condition that the heat exchange capacity of the system is weaker than that of the outdoor radiator 15 when the first heat recoverer 9 is used as an evaporator is judged according to related parameters.

TABLE 3 second heating mode control logic

The third heating mode includes the following control processes: when T1min is less than or equal to T1 and less than T2min, the first electromagnetic valve 12 and the third electromagnetic valve 13 are opened, and the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are closed; when T2min is less than or equal to T1 and less than T2min + delta T1, the third electromagnetic valve 13 is opened, and the first electromagnetic valve 12, the second electromagnetic valve 14 and the fourth electromagnetic valve 16 are closed; when T1 is more than or equal to T2min + delta T1 and less than T2min + delta T2, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are opened, and the first electromagnetic valve 12 and the second electromagnetic valve 14 are closed; when T2min + delta T2 is not less than T1 and is less than T2 max-delta T3, the second electromagnetic valve 14, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are opened, and the first electromagnetic valve 12 is closed; when T2 max-delta T3 is not less than T1 and T2 max-delta T4, the second electromagnetic valve 14, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are opened, the first electromagnetic valve 12 is closed, and meanwhile, the rotating speed of the fan of the outdoor radiator 15 is increased; when T2 max-delta T4 is not less than T1 and is less than T2max, the second electromagnetic valve 14, the third electromagnetic valve 13 and the fourth electromagnetic valve 16 are opened, the first electromagnetic valve 12 is closed, and meanwhile, the rotating speed of the gas engine 1 is reduced; when T1 is more than or equal to T2max and lasts for T1 time, the gas engine 1 is stopped; as shown in table 4 below. When the related parameters judge that the heat exchange capacity of the system is stronger than that of the outdoor radiator 15 when the first heat recoverer 9 is used as an evaporator, the system is generally present at low ambient temperature, such as minus 10 ℃ and below, and the system is suitable for a cold and hot water machine with a third heat recoverer 17.

TABLE 4 third heating mode control logic

Wherein, Δ T1, Δ T2, Δ T3 and Δ T4 are design temperature differences, specifically, Δ T1, Δ T2, Δ T3 and Δ T4 refer to control intervals of specific electromagnetic valve switch combinations, and the switches of the electromagnetic valves are controlled according to the temperature intervals of the cooling water temperature T1. T1min is the lowest temperature of cooling water recovery, T1 is higher than T1min and can begin to recover cooling water heat, otherwise the temperature of cooling water returning to the engine is low, which is not beneficial to the work of the engine. T2min is the minimum recovery temperature T1min of the cooling water plus a preset heat exchanger temperature difference, and if the minimum recovery temperature T1min of the cooling water is 30 degrees and the preset heat exchanger temperature difference is 5 degrees (enough temperature difference can make the heat recovery process smoother), T2min is 35 degrees. T2max is the cooling water overheat protection temperature, and if it exceeds this value, the engine is damaged by the excessively high cooling water temperature. The above concept of temperature design is conventional writing and can be recognized by those skilled in the art.

The control period of the solenoid valve is t2, and is generally set to 30 seconds. The control process of the electromagnetic valve is smooth, and the severe fluctuation of cooling water is prevented.

Wherein T1min, T2min and T2max are related to the selection of the outdoor heat exchanger and the heat recoverer 1/2, the temperature of the cooling water returned to the engine is lower when T1 is smaller than Tmin, and the temperature of the cooling water returned to the engine is too high when T1 is larger than Tmax, which are both unfavorable for the operation of the engine. Δ T1, Δ T2, Δ T3, Δ T4 are design temperature differences.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.