Automobile air conditioning system based on liquid ammonia cold energy

Abstract

The invention is suitable for the technical field of automobile air conditioning systems, and provides an automobile air conditioning system based on liquid ammonia cold energy, which comprises an ammonia engine unit, an air conditioning unit and an air distribution unit, the air distribution unit comprises an air blower, the air blower is connected with a warm air heat exchanger and an evaporator through a flow dividing valve, the warm air heat exchanger is connected with a liquid ammonia evaporation box, air is conveyed out of a vehicle through the liquid ammonia evaporation box, and the warm air heat exchanger is further directly connected with the interior of the vehicle through an air conditioner air channel. And an air channel temperature sensor is further arranged at the air conditioner air channel. According to the system, the cooling capacity of liquid ammonia evaporation is utilized, so that the working requirement of an air conditioner is reduced, and the energy loss of an ammonia engine can be effectively reduced; meanwhile, the temperature of the liquid ammonia evaporation box is maintained through waste heat of the ammonia engine, the situation that the evaporation efficiency is affected by supercooling of the liquid ammonia evaporation box is effectively prevented, stable operation of the ammonia engine is guaranteed, and meanwhile the energy requirement for guaranteeing the temperature of the liquid ammonia evaporation box is lowered.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile air-conditioning systems, and in particular relates to an automobile air-conditioning system based on liquid ammonia cooling energy. Background Art

[0002] Automobile emissions account for a high proportion of the entire transportation industry emissions, so exploring the green transformation of internal combustion engines is one of the current focuses. Energy conservation, emission reduction and efficient use of energy will be the theme for a long time in the future. Ammonia has no carbon atoms in the fuel, and combustion does not produce carbon dioxide. It has a high energy density and is considered to be one of the most promising internal combustion engine fuels. At the same time, the storage and transportation technology of ammonia is very mature, and it is generally stored in the form of liquid ammonia on vehicles.

[0003] The process of converting liquid ammonia into ammonia gas is a physical process of gasification and heat absorption. At the same time, the ammonia engine continuously needs ammonia gas during operation, so this heat absorption process is carried out continuously. Air convection during vehicle operation will take away some of the cold, but it is still easy to cause the temperature of the liquid ammonia evaporator to drop or even freeze, thus affecting the evaporation effect of the liquid ammonia.

[0004] Car air conditioners are high-energy-consuming accessories, accounting for 10%-20% of vehicle energy consumption, half of which is used to drive the refrigeration compressor. The commonly used refrigerant is R134a, with a latent heat of vaporization of 215kJ / kg. In ammonia engines, since ammonia is used as fuel, liquid ammonia evaporates continuously, and the latent heat of vaporization of liquid ammonia is 1369kJ / kg, which is about seven times that of R134a, so it is an excellent refrigerant. At present, liquid ammonia is mainly used as a refrigerant in cold storage, and has also been successfully applied in industry. Although some scholars have conducted research on the utilization of cold energy in marine ammonia engines, the system is too complicated to be applied in automobiles, and there is still a lack of relevant research on automobiles. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide an automobile air-conditioning system based on liquid ammonia cooling energy, aiming to solve the problems raised in the above-mentioned background technology.

[0006] The embodiment of the present invention is implemented as follows: an automobile air conditioning system based on liquid ammonia cooling energy includes an ammonia engine unit, an air conditioning unit, and an air distribution unit;

[0007] The ammonia engine unit comprises an ammonia tank, a liquid ammonia evaporation tank and an ammonia engine. The liquid ammonia evaporation tank and the ammonia engine are both arranged at the front side of the vehicle. The ammonia tank is connected to the liquid ammonia evaporation tank via a pipeline, and a liquid ammonia pump, a liquid ammonia pressure sensor and an expansion valve are sequentially arranged on the pipeline. The liquid ammonia evaporation tank is also provided with a first temperature sensor. The liquid ammonia evaporation tank and the ammonia engine are also connected via a pipeline, and a pressure stabilizing tank, an ammonia flow meter and an ammonia temperature sensor are sequentially arranged on the pipeline.

[0008] The air conditioning unit comprises an evaporator, a compressor, a condenser, a drying bottle and an expansion valve connected in sequence, a second temperature sensor is arranged on the evaporator, a fan and an outside temperature sensor are also installed at the condenser, and a pressure sensor is also arranged between the condenser and the drying bottle;

[0009] The air distribution unit includes a blower, which is respectively connected to a warm air heat exchanger and an evaporator through a diverter valve. The warm air heat exchanger is connected to a liquid ammonia evaporator tank, and the gas is transported to the outside of the vehicle through the liquid ammonia evaporator tank. The warm air heat exchanger is also directly connected to the interior of the vehicle through an air-conditioning air duct, and an air duct temperature sensor is also provided at the air-conditioning air duct. An in-vehicle temperature sensor is also provided in the vehicle.

[0010] The liquid ammonia evaporation box comprises a liquid ammonia evaporation box shell, in which a liquid ammonia delivery pipe and a gas delivery pipe are arranged, the liquid ammonia delivery pipe and the gas delivery pipe are both S-shaped, the liquid ammonia delivery pipe is placed horizontally, and the gas delivery pipe is placed vertically, a plurality of fins are further arranged inside the liquid ammonia evaporation box shell, and the first temperature sensor is installed on the fins.

[0011] Another object of the embodiment of the present invention is to provide a control method for an automobile air conditioning system based on liquid ammonia cooling energy, which is as follows:

[0012] (1) When the passenger does not turn on the air conditioner:

[0013] In the current mode, the main work content of the system is to achieve the stability of the fuel supply at the inlet end of the ammonia engine. The temperature control logic diagram of the liquid ammonia evaporator is shown in the figure. The liquid ammonia pressure sensor and the first temperature sensor are used to detect the pressure of liquid ammonia and the temperature of the liquid ammonia evaporator. Compare with the preset temperature and pressure. If the pressure is lower than the preset pressure, it is judged that the amount of ammonia tank is insufficient at this time, and fuel needs to be replenished immediately. If the temperature is lower than the preset temperature at this time, the liquid ammonia evaporator needs to be heated at this time, the blower is turned on, and the gas passes through the left gas path through the diverter valve. The valve from the engine cooling water to the warm air heat exchanger is opened, and the air flows through the warm air heat exchanger to heat the air. The air with the increased temperature flows through the liquid ammonia evaporator to increase the temperature of the liquid ammonia evaporator and keep the temperature stable. Since the passenger did not turn on the air conditioning system, the excess gas was directly discharged outside the car.

[0014] (2) When the passenger turns on the air conditioner and selects cooling mode:

[0015] In this mode, the main task of the air conditioning unit is to meet the cooling needs of the passengers and prevent the liquid ammonia evaporator from freezing, which affects the evaporation efficiency of the liquid ammonia. Therefore, the temperature of the liquid ammonia evaporator needs to be monitored in this mode and heated when necessary. The outside temperature sensor on the condenser in the air conditioning unit is used to identify the ambient temperature outside the vehicle at this time, and a target temperature is set according to the needs of the passengers. The cooling needs of the air conditioning unit at this time are judged based on the temperature difference. The temperature inside the vehicle is detected by the in-vehicle temperature sensor and compared with the target temperature range to determine whether the working state needs to be changed at this time, thereby determining the target value of the air temperature in the air conditioning duct. The air temperature of the air conditioning duct is monitored by the air duct temperature sensor and compared with the target range to determine whether the cooling capacity at this time meets the demand. The control logic diagram in the air conditioning cooling mode is shown in the figure.

[0016] When the difference between the outside temperature and the target temperature is not large, the cooling capacity required by the vehicle is small, and the liquid ammonia evaporator can complete the task by working alone. At this time, there is no need to start the refrigeration cycle. The air flows into the left passage through the diverter valve, passes through the warm air heat exchanger, flows through the liquid ammonia evaporator, and makes the cooling air reach the end of the air conditioning duct, and then enters the car. According to the temperature of the liquid ammonia evaporator, it is judged whether the warm air heat exchanger needs to be turned on. At this time, the device status is judged by the parameters received in the ECU. If the air temperature of the air conditioning duct is lower than the target value, the cooling capacity is too much at this time, which may cause the temperature in the car to be too low or the air blowing is too cold, resulting in a decrease in the passenger experience. The diverter valve should be adjusted to allow the outside air to enter the air conditioning duct through the right channel and mix with the refrigerated air to reach the target temperature. If the air temperature of the air conditioning duct is equal to the target temperature value, the cooling capacity is just right at this time, and no additional operation is required. If the air temperature of the air conditioning duct is higher than the target value, the cooling capacity is too small at this time, and the cooling capacity needs to be increased. By adjusting the diverter valve, the amount of air flowing to the right is reduced to reduce the air temperature.

[0017] When the difference between the outside temperature and the target temperature is large, the vehicle requires a large amount of cooling capacity, and the liquid ammonia evaporator alone cannot meet the cooling capacity requirements. At this time, the refrigeration cycle needs to be turned on, and the air flows into the channels on both sides through the diverter valve according to demand. When the air flows through the left side, the air temperature is reduced to a certain temperature and mixed with the air flowing through the refrigeration cycle to reach the target temperature. The temperature of the air flowing into the vehicle is monitored based on the airway temperature sensor. When the temperature of the airway temperature sensor is lower than the preset temperature range, it means that the cooling capacity is too much at this time, and it is necessary to reduce the power of the compressor, reduce the cooling capacity, and increase the temperature of the air in the airway. When the temperature of the airway temperature sensor is in the preset temperature range, it means that the cooling capacity meets the requirements at this time, and no additional operation is required. When the temperature of the airway temperature sensor is higher than the preset temperature range, it means that the cooling capacity is low at this time and the cooling capacity needs to be increased. At this time, the power of the compressor needs to be increased to increase the cooling capacity.

[0018] (3) When the passenger turns on the air conditioner and selects the heating mode:

[0019] In heating mode, the main function of the air conditioning unit is to provide warm air to the car to ensure the comfort of the interior space, while also preventing the temperature of the liquid ammonia evaporator from being too low. The state judgment method of heating mode is the same as that of cooling mode. It is judged by the relationship between the temperatures of various temperature sensors. The target range of the air temperature in the air conditioning duct is determined based on passenger demand and outdoor temperature, and compared with the temperature reading of the duct temperature sensor. Temperature control is achieved by adjusting the airflow direction and various components.

[0020] Since the air conditioning unit is in heating mode, it is necessary to open the valve from the engine cooling water to the warm air heat exchanger to allow air to flow through the warm air heat exchanger. The air then flows in two directions. One direction is directly into the car to heat the air inside the car. The other direction is the liquid ammonia evaporator to prevent the temperature of the liquid ammonia evaporator from being too low. The air then flows into the outside or inside of the car according to the situation. The control logic diagram of the air conditioning heating mode is shown in the figure.

[0021] When the difference between the outside temperature and the target temperature is small, the heating amount required by the air conditioner is small. At this time, the heat of the engine waste heat is relatively large, and the temperature of the air duct temperature sensor must be higher than the expected temperature range. If it is directly introduced into the car, it will inevitably reduce the comfort of the passengers. Therefore, some cold air needs to be introduced to cool the hot air. According to the needs, part of the air flowing through the liquid ammonia evaporator is discharged to the outside of the car, and part of it enters the air duct of the air conditioner and mixes with the hot air to reduce the air temperature in the air duct of the air conditioner so that the air duct temperature is maintained in the target range. If the air of the liquid ammonia evaporator is fully introduced into the air duct of the air conditioner, and the temperature of the air duct temperature sensor is still higher than the upper limit of the preset temperature range, the cooling capacity of the liquid ammonia evaporation is not enough to reduce the air temperature to the target temperature. It is necessary to introduce part of the air into the right flow direction, do not start the refrigeration cycle first, and rely on cold air for cooling. If it still cannot meet the needs, start the refrigeration cycle and rely on the refrigeration cycle to increase the cooling capacity to reduce the air temperature to the target range. When the temperature of the air duct temperature sensor is in the preset temperature range, it means that it meets the requirements at this time and no additional operation is required. When the temperature of the air duct temperature sensor is lower than the preset temperature range, it means that there is too much cold air at this time. The cooling capacity of the refrigeration cycle is reduced first, then the amount of cold air is reduced, and finally the liquid ammonia cooling capacity is reduced to reduce the cooling capacity and maintain the temperature within the target range.

[0022] When the difference between the outside temperature and the target temperature is large, the air conditioning unit requires a large amount of heating. At this time, less cold energy is needed to neutralize the heat, and the cold energy of liquid ammonia evaporation can meet the demand. As the ambient temperature outside the vehicle further decreases, the effect of heating the liquid ammonia evaporator box by air convection generated by the car's driving will decrease. At this time, more engine waste heat is needed to keep the temperature of the liquid ammonia evaporator box stable. When the temperature of the airway temperature sensor is higher than the preset temperature range, it means that the amount of cold air is too small at this time, and the cold energy of liquid ammonia needs to be increased to flow into the air conditioning airway to keep the temperature within the target range. When the temperature of the airway temperature sensor is within the preset temperature range, it means that the working condition is good at this time and no additional operation is required. When the temperature of the airway temperature sensor is lower than the preset temperature range, it means that the amount of cold air is too large at this time, and the cold energy of liquid ammonia needs to be reduced to flow into the air conditioning airway to keep the temperature within the target range.

[0023] An automobile air conditioning system based on liquid ammonia cooling energy provided by an embodiment of the present invention has the following beneficial effects:

[0024] (1) The cooling capacity of liquid ammonia evaporation is utilized to reduce the working requirements of the air conditioner and effectively reduce the energy loss of the ammonia engine;

[0025] (2) The refrigeration cycle can be designed to be more compact, which can effectively save space in the vehicle.

[0026] (3) The waste heat of the ammonia engine is used to maintain the temperature of the liquid ammonia evaporator, which effectively prevents the liquid ammonia evaporator from being overcooled and affecting the evaporation efficiency, ensuring the stable operation of the ammonia engine. At the same time, it reduces the energy demand for the liquid ammonia evaporator to maintain the temperature, and can reduce the size of the liquid ammonia evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of an automobile air conditioning system based on liquid ammonia cooling energy provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the structure of a liquid ammonia evaporator in an automobile air-conditioning system based on liquid ammonia cooling energy provided by an embodiment of the present invention;

[0029] Figure 3 A temperature control logic diagram of a liquid ammonia evaporator of an automobile air conditioning system based on liquid ammonia cooling energy provided by an embodiment of the present invention;

[0030] Figure 4 A control logic diagram of a vehicle air conditioning system based on liquid ammonia cooling energy in a cooling mode provided by an embodiment of the present invention;

[0031] Figure 5 A heating mode control logic diagram of an automobile air-conditioning system based on liquid ammonia cooling energy is provided in an embodiment of the present invention.

[0032] In the accompanying drawings: an ammonia tank 1; a liquid ammonia pump 2; a liquid ammonia pressure sensor 3; an expansion valve 4; a liquid ammonia evaporation box 5; a first temperature sensor 6; a warm air heat exchanger 7; a diverter valve 8; a blower 9; an evaporator 10; a second temperature sensor 11; a compressor 12; a condenser 13; a fan 14; an outside temperature sensor 15; a pressure sensor 16; a drying bottle 17; an expansion valve 18; inside the vehicle 19; an inside temperature sensor 20; an airway temperature sensor 21; outside the vehicle 22; a pressure regulating tank 23; an ammonia flowmeter 24; an ammonia temperature sensor 25; an ammonia engine 26; a liquid ammonia delivery pipe 27; a gas delivery pipe 28; a fin 29; and a liquid ammonia evaporation box housing 30. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0035] like Figure 1 As shown, an automobile air conditioning system based on liquid ammonia cooling energy provided by one embodiment of the present invention includes an ammonia engine unit, an air conditioning unit and an air distribution unit;

[0036] The ammonia engine unit comprises an ammonia tank 1, a liquid ammonia evaporation tank 5 and an ammonia engine 26. The liquid ammonia evaporation tank 5 and the ammonia engine 26 are both arranged at the front side of the vehicle. The ammonia tank 1 is connected to the liquid ammonia evaporation tank 5 by a pipeline, and a liquid ammonia pump 2, a liquid ammonia pressure sensor 3 and an expansion valve 4 are arranged on the pipeline in sequence. The liquid ammonia evaporation tank 5 is also provided with a first temperature sensor 6. The liquid ammonia evaporation tank 5 and the ammonia engine 26 are also connected by a pipeline, and a pressure stabilizing tank 23, an ammonia flowmeter 24 and an ammonia temperature sensor 25 are arranged on the pipeline in sequence.

[0037] The air conditioning unit comprises an evaporator 10, a compressor 12, a condenser 13, a drying bottle 17 and an expansion valve 18 which are connected in sequence. A second temperature sensor 11 is arranged on the evaporator 10, a fan 14 and an outside temperature sensor 15 are also installed at the condenser 13, and a pressure sensor 16 is also arranged between the condenser 13 and the drying bottle 17;

[0038] The air distribution unit includes a blower 9, which is connected to a warm air heat exchanger 7 and an evaporator 10 respectively through a diverter valve 8. The warm air heat exchanger 7 is connected to a liquid ammonia evaporator tank 5, and the gas is transported to the outside of the vehicle 22 through the liquid ammonia evaporator tank 5. The warm air heat exchanger 7 is also directly connected to the interior of the vehicle 19 through an air-conditioning air duct, and an air duct temperature sensor 21 is also provided at the air-conditioning air duct. The interior of the vehicle 19 is also provided with an interior temperature sensor 20.

[0039] In the embodiment of the present invention, the liquid ammonia evaporator 5 is combined with the automobile air conditioner. The coldness of the evaporated liquid ammonia is used to reduce the power output of the engine during cooling, thereby achieving the purpose of reducing fuel consumption. At the same time, the engine waste heat is also used to ensure the stability of ammonia when entering the engine, prevent the liquid ammonia evaporator 5 from freezing, and increase the stability of the operation of the ammonia engine 26.

[0040] The liquid ammonia in the ammonia tank 1 flows into the pipeline through the liquid ammonia pump 2, flows through the liquid ammonia pressure sensor 3, enters the expansion valve 4 for expansion and pressure reduction, and then enters the liquid ammonia evaporation tank 5 to start evaporation. The first temperature sensor 6 provided on the liquid ammonia evaporation tank 5 is used to judge the temperature of the liquid ammonia evaporation tank 5. The ammonia that has been evaporated in the liquid ammonia evaporation tank 5 flows through the pressure regulating tank 23, the ammonia flowmeter 24 and the ammonia temperature sensor 25, which are used to detect the state of ammonia at the intake end of the ammonia engine 26 to ensure the intake state of the ammonia engine 26.

[0041] In the air conditioning unit, the coolant realizes the refrigeration function through the steps of expansion, evaporation, compression, cooling and drying, and is equipped with an outside temperature sensor 15 to detect the outside temperature at this time. Compared with the traditional automobile air conditioning, since the cold energy of liquid ammonia is used to reduce the demand for refrigeration capacity, a more compact device can be used when designing the refrigeration cycle device, which can save space in the car.

[0042] In the air distribution unit, air is sucked into the air duct by the blower 9, and the flow direction of the gas is controlled by the diverter valve 8. The gas is mainly divided into two flows, one is the traditional refrigeration cycle (that is, directly delivered to the air conditioning unit), and the other is to pass the air into the warm air heat exchanger 7, and the flow direction of the air is controlled according to the device status and passenger needs, through the liquid ammonia evaporator 5 or directly into the car air conditioning intake duct. At the end of the air conditioning duct, the air duct temperature sensor 21 at the end of the air conditioning duct is used to detect the temperature of the gas entering the car to determine whether the air conditioning working state meets the requirements. At the same time, the temperature inside the car is detected in real time by the in-car temperature sensor 20.

[0043] like Figure 2 As shown, as a preferred embodiment of the present invention, the liquid ammonia evaporation box 5 includes a liquid ammonia evaporation box shell 30, and a liquid ammonia delivery pipe 27 and a gas delivery pipe 28 are arranged in the liquid ammonia evaporation box shell 30. The liquid ammonia delivery pipe 27 and the gas delivery pipe 28 are both S-shaped, and the liquid ammonia delivery pipe 27 is placed horizontally, and the gas delivery pipe 28 is placed vertically. A plurality of fins 29 are also arranged inside the liquid ammonia evaporation box shell 30, and the first temperature sensor 6 is installed on the fins 29.

[0044] In the embodiment of the present invention, liquid ammonia enters from one end of the liquid ammonia delivery pipe 27, expands through heat absorption, becomes gaseous, and flows out from the other end of the liquid ammonia delivery pipe 27. In this process, liquid ammonia exchanges heat with the liquid ammonia delivery pipe 27, and the liquid ammonia delivery pipe 27 exchanges heat with the surrounding air through the fins 29. During the driving of the car, the fins take away part of the heat by forced convection with the air, and the first temperature sensor 6 is used to detect the temperature of the fins to prevent the temperature from being too low. The air in the air conditioning duct enters the liquid ammonia evaporator through one end of the gas delivery pipe 28, exchanges heat with the fins 29 to increase the temperature of the fins 29, and flows out through the other end of the gas delivery pipe 28, and then flows to the outside or inside of the car according to demand.

[0045] Working principle: The system mainly collects data through various sensors installed in different positions and transmits the data to the ECU. The ECU determines the working status based on the collected data and then controls the entire system to achieve the cooling and heating functions of the air conditioning unit and maintain the stability of the gas at the engine inlet. The ECU determines the passenger's needs at this time based on the air conditioning mode selected by the passenger and the sensor data and controls the entire system. The specific implementation plan is as follows:

[0046] (1) When the passenger does not turn on the air conditioner:

[0047] In the current mode, the main work content of the system is to achieve the stability of the fuel supply at the inlet end of the ammonia engine 26. The temperature control logic diagram of the liquid ammonia evaporator 5 is as follows: Figure 3 As shown. The liquid ammonia pressure sensor 3 and the first temperature sensor 6 are used to detect the pressure of liquid ammonia and the temperature of the liquid ammonia evaporator 5. Compare with the preset temperature and pressure. If the pressure is lower than the preset pressure, it is judged that the amount of ammonia tank 1 is insufficient at this time, and fuel needs to be replenished immediately. If the temperature is lower than the preset temperature at this time, the liquid ammonia evaporator 5 needs to be heated, the blower 9 is turned on, and the gas passes through the left gas path through the diverter valve 8, and the valve from the engine cooling water to the warm air heat exchanger 7 is opened. The air flows through the warm air heat exchanger 7 to heat the air. The air with the increased temperature flows through the liquid ammonia evaporator 5 to increase the temperature of the liquid ammonia evaporator 5 and keep the temperature stable. Since the passenger did not turn on the air conditioning system, the excess gas was directly discharged outside the vehicle.

[0048] (2) When the passenger turns on the air conditioner and selects cooling mode:

[0049] In this mode, the main task of the air-conditioning unit is to meet the cooling needs of the passengers, while preventing the liquid ammonia evaporator 5 from freezing and affecting the evaporation efficiency of the liquid ammonia. Therefore, in this mode, it is necessary to monitor the temperature of the liquid ammonia evaporator 5 and perform heating when necessary. The outside temperature sensor 15 on the condenser 13 in the air-conditioning unit is used to identify the ambient temperature outside the vehicle at this time, and a target temperature is set according to the needs of the passengers. The cooling needs of the air-conditioning unit at this time are judged based on the temperature difference. The inside temperature sensor 20 detects the inside temperature of the vehicle and compares it with the target temperature range to determine whether the working state needs to be changed at this time, thereby determining the target value of the air temperature in the air-conditioning duct. The air temperature of the air-conditioning duct is monitored by the air duct temperature sensor 21 and compared with the target range to determine whether the cooling capacity at this time meets the demand. The control logic diagram under the air-conditioning refrigeration mode is shown in the figure below. Figure 4 shown.

[0050] When the difference between the outside temperature and the target temperature is not very large (the specific temperature difference range can be set according to the actual situation), the cooling capacity required by the vehicle is small, and the liquid ammonia evaporator 5 can complete the task by working alone. At this time, there is no need to start the refrigeration cycle. The air flows into the left passage through the diverter valve 8, passes through the warm air heat exchanger 7, flows through the liquid ammonia evaporator 5, and the cooling air reaches the end of the air conditioning duct, and then enters the car 19. According to the temperature of the liquid ammonia evaporator 5, it is judged whether the warm air heat exchanger 7 needs to be turned on. At this time, the device status is judged by the parameters received in the ECU. If the air temperature of the air conditioning duct is lower than the target value, the cooling capacity is too much at this time, which may cause the temperature in the car to be too low or the wind is too cold, resulting in a decrease in the passenger experience. The diverter valve 8 should be adjusted to allow the outside air to enter the air conditioning duct through the right channel and mix with the refrigerated air to reach the target temperature. If the air temperature of the air conditioning duct is equal to the target temperature value, the cooling capacity is just right at this time, and no additional operation is required. If the air temperature in the air conditioning duct is higher than the target value, the cooling capacity is too small and needs to be increased. By adjusting the diverter valve 8, the amount of air flowing to the right side is reduced to lower the air temperature.

[0051] When the difference between the outside temperature and the target temperature is large, the refrigeration capacity required by the vehicle is large, and the liquid ammonia evaporator 5 working alone cannot meet the refrigeration capacity requirement. At this time, the refrigeration cycle needs to be turned on, and the air flows into the channels on both sides according to demand through the diverter valve 8. When the air flows through the left side, the air temperature is reduced to a certain temperature and mixed with the air flowing through the refrigeration cycle to reach the target temperature. The temperature of the air flowing into the vehicle is monitored based on the airway temperature sensor 21. When the temperature of the airway temperature sensor 21 is lower than the preset temperature range, it means that the refrigeration capacity is too much at this time, and it is necessary to reduce the power of the compressor 12, reduce the refrigeration capacity, and increase the temperature of the air in the airway. When the temperature of the airway temperature sensor 21 is in the preset temperature range, it means that the refrigeration capacity meets the requirements at this time and no additional operation is required. When the temperature of the airway temperature sensor 21 is higher than the preset temperature range, it means that the refrigeration capacity is low at this time and the refrigeration capacity needs to be increased. At this time, the power of the compressor 12 needs to be increased to increase the refrigeration capacity.

[0052] (3) When the passenger turns on the air conditioner and selects the heating mode:

[0053] In the heating mode, the main function of the air conditioning unit is to provide warm air to the interior of the vehicle 19 to ensure the comfort of the interior space, while also preventing the temperature of the liquid ammonia evaporator 5 from being too low. The state judgment method of the heating mode is the same as that of the cooling mode. The judgment is made through the relationship between the temperatures of various temperature sensors. The target range of the air temperature in the air conditioning air duct is determined according to the passenger demand and the outdoor temperature, and compared with the temperature reading of the air duct temperature sensor 21. The temperature control is achieved by adjusting the airflow direction and various components.

[0054] Since the air conditioning unit is in heating mode, it is necessary to open the valve from the engine cooling water to the warm air heat exchanger 7, so that the air flows through the warm air heat exchanger 7, and then the air flows in two directions. One direction is directly into the vehicle 19 to heat the air inside the vehicle. The other direction is the liquid ammonia evaporation tank 5 to prevent the temperature of the liquid ammonia evaporation tank 5 from being too low. Then the air is selected to flow into the outside of the vehicle 22 or into the vehicle 19 according to the situation. The air conditioning heating mode control logic diagram is shown in the figure below. Figure 5 shown.

[0055] When the difference between the outside temperature and the target temperature is small, the heating amount required by the air conditioner is small. At this time, the heat of the engine waste heat is relatively large. The temperature of the air duct temperature sensor 21 must be higher than the expected temperature range. If it is directly introduced into the car, it will inevitably reduce the comfort of the passengers. Therefore, it is necessary to introduce some cold air to cool the hot air. According to the needs, part of the air flowing through the liquid ammonia evaporator 5 is discharged to the outside of the car, and part of it enters the air conditioning air duct and mixes with the hot air to reduce the air temperature in the air conditioning air duct so that the air conditioning air duct temperature is maintained in the target range. If the air of the liquid ammonia evaporator 5 is fully introduced into the air conditioning air duct, the temperature of the air duct temperature sensor 21 is still higher than the upper limit of the preset temperature range, and the refrigeration capacity of the liquid ammonia evaporation is not enough to reduce the air temperature to the target temperature. It is necessary to introduce part of the air into the right flow direction, do not start the refrigeration cycle first, and rely on cold air for cooling. If it still cannot meet the needs, start the refrigeration cycle, and rely on the refrigeration cycle to increase the cold capacity to reduce the air temperature to the target range. When the temperature of the air duct temperature sensor 21 is in the preset temperature range, it means that it meets the requirements at this time and no additional operation is required. When the temperature of the air duct temperature sensor 21 is lower than the preset temperature range, it means that there is too much cold air at this time. The cooling capacity of the refrigeration cycle is first reduced, then the amount of cold air is reduced, and finally the liquid ammonia cooling capacity is reduced to maintain the temperature within the target range.

[0056] When the difference between the outside temperature and the target temperature is large, the heating amount required by the air conditioning unit is large. At this time, the cold amount needed to neutralize the heat is less, and the cold amount of liquid ammonia evaporation can meet the demand. As the ambient temperature outside the vehicle further decreases, the effect of heating the liquid ammonia evaporator 5 using the air convection generated by the car's driving will decrease. At this time, more engine waste heat is needed to maintain the temperature stability of the liquid ammonia evaporator 5. When the temperature of the airway temperature sensor 21 is higher than the preset temperature range, it means that the amount of cold air is too small at this time, and the cold amount of liquid ammonia needs to be increased to flow into the air conditioning airway to maintain the temperature within the target range. When the temperature of the airway temperature sensor 21 is in the preset temperature range, it means that the working state is good at this time and no additional operation is required. When the temperature of the airway temperature sensor 21 is lower than the preset temperature range, it means that the amount of cold air is too much at this time, and the cold amount of liquid ammonia is reduced to flow into the air conditioning airway to maintain the temperature within the target range.

[0057] (4) The impact of different working conditions on refrigeration effect:

[0058] The ammonia engine 26 has different ammonia requirements under different working conditions. The working conditions of the ammonia engine 26 are mainly divided into idling, small and medium loads, large loads, full loads, acceleration conditions and deceleration conditions. The difference between the first four is that the ammonia flow values ​​are different, but the flow is almost stable. In the acceleration condition, in order to meet the acceleration demand, the ammonia demand is increased, and for the deceleration condition, the ammonia demand is reduced. At the same time, the change of ammonia flow will also cause the change of the cooling capacity of the liquid ammonia evaporator.

[0059] When the air conditioning unit is running, the engine operating condition at this time is determined according to the ammonia flow meter 24. During the use of the air conditioner, stable cooling capacity is the key to maintaining system stability. Therefore, for the first four operating conditions, the main impact is the heat absorbed by the evaporation process of liquid ammonia during use, which belongs to a stable state. According to the cooling capacity corresponding to different ammonia flow rates, combined with the above strategies, it is easy to maintain system stability.

[0060] Under the acceleration condition, the ammonia flow demand increases. At this time, the heat absorbed by the evaporation of liquid ammonia increases, which may cause the temperature of the liquid ammonia evaporation tank 5 to be too low, affecting the evaporation efficiency. At this time, it is necessary to compare the temperature of the first temperature sensor 6 on the liquid ammonia evaporation tank 5 with the preset temperature to determine whether the heating mode needs to be adopted.

[0061] Under deceleration conditions, the ammonia flow demand decreases. At this time, the heat absorbed by the evaporation of liquid ammonia decreases, which may affect the refrigeration mode. The temperature of the air duct temperature sensor 21 is used to determine whether the refrigeration cycle needs to be started or other measures need to be taken.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An automobile air conditioning system based on liquid ammonia cooling energy, characterized in that: including an ammonia engine unit, an air conditioning unit, and an air distribution unit; The ammonia engine unit comprises an ammonia tank, a liquid ammonia evaporation tank and an ammonia engine. The liquid ammonia evaporation tank and the ammonia engine are both arranged at the front side of the vehicle. The ammonia tank is connected to the liquid ammonia evaporation tank via a pipeline, and a liquid ammonia pump, a liquid ammonia pressure sensor and an expansion valve are sequentially arranged on the pipeline. The liquid ammonia evaporation tank is also provided with a first temperature sensor. The liquid ammonia evaporation tank and the ammonia engine are also connected via a pipeline, and a pressure stabilizing tank, an ammonia flow meter and an ammonia temperature sensor are sequentially arranged on the pipeline. The air conditioning unit comprises an evaporator, a compressor, a condenser, a drying bottle and an expansion valve connected in sequence, a second temperature sensor is arranged on the evaporator, a fan and an outside temperature sensor are also installed at the condenser, and a pressure sensor is also arranged between the condenser and the drying bottle; The air distribution unit includes a blower, which is respectively connected to a warm air heat exchanger and an evaporator through a diverter valve. The warm air heat exchanger is connected to a liquid ammonia evaporator tank, and the gas is transported to the outside of the vehicle through the liquid ammonia evaporator tank. The warm air heat exchanger is also directly connected to the interior of the vehicle through an air-conditioning air duct, and an air duct temperature sensor is also provided at the air-conditioning air duct. An in-vehicle temperature sensor is also provided in the vehicle.

2. The automobile air conditioning system based on liquid ammonia cooling energy according to claim 1, characterized in that: The liquid ammonia evaporation box comprises a liquid ammonia evaporation box shell, in which a liquid ammonia delivery pipe and a gas delivery pipe are arranged, the liquid ammonia delivery pipe and the gas delivery pipe are both S-shaped, the liquid ammonia delivery pipe is placed horizontally, and the gas delivery pipe is placed vertically, a plurality of fins are further arranged inside the liquid ammonia evaporation box shell, and the first temperature sensor is installed on the fins.

3. The automobile air conditioning system based on liquid ammonia cooling energy according to claim 2, characterized in that: When the passenger does not turn on the air conditioning unit, the liquid ammonia pressure sensor and the first temperature sensor are used to detect the pressure of the liquid ammonia and the temperature of the liquid ammonia evaporator, and compare them with the preset temperature and pressure: If the pressure is lower than the preset pressure, it is judged that the amount of ammonia in the ammonia tank is insufficient and fuel needs to be refilled immediately; if the temperature is lower than the preset temperature, the liquid ammonia evaporator tank needs to be heated, the blower is turned on, and the gas is allowed to pass through the left gas path through the diverter valve. The valve from the engine cooling water to the warm air heat exchanger is opened, and the air flows through the warm air heat exchanger to heat the air. The air with increased temperature flows through the liquid ammonia evaporator tank to increase the temperature of the liquid ammonia evaporator tank, so that the temperature remains stable, and the excess gas is directly discharged outside the vehicle.

4. The automobile air conditioning system based on liquid ammonia cooling energy according to claim 2, characterized in that: When the passenger turns on the air conditioning unit and selects the cooling mode, the outside temperature sensor on the condenser of the air conditioning unit is used to identify the ambient temperature outside the vehicle at this time, and a target temperature is set according to the passenger's needs. The cooling demand of the air conditioning unit at this time is judged based on the temperature difference. The inside temperature sensor is used to detect the inside temperature of the vehicle and compare it with the target temperature range to determine whether the working state needs to be changed at this time, thereby determining the target value of the air temperature in the air conditioning duct; the air duct temperature sensor is used to monitor the air temperature of the air conditioning duct and compare it with the target range to determine whether the cooling capacity at this time meets the demand; When the difference between the outside temperature and the target temperature is small, the cooling capacity required by the vehicle is small, and the liquid ammonia evaporator can complete the task by working alone. At this time, there is no need to start the refrigeration cycle; the air flows into the left passage through the diverter valve, passes through the warm air heat exchanger, flows through the liquid ammonia evaporator, and the cooled air reaches the end of the air conditioning duct and then enters the vehicle; according to the temperature of the liquid ammonia evaporator, it is judged whether the warm air heat exchanger needs to be turned on. At this time, the device status is judged by the parameters received in the ECU: if the air temperature of the air conditioning duct is lower than the target value, the cooling capacity is too much at this time, and the diverter valve is adjusted to allow the outside air to enter the air conditioning duct through the right channel and mix with the refrigerated air to reach the target temperature; if the air temperature of the air conditioning duct is equal to the target temperature value, the cooling capacity is just right at this time, and no additional operation is required; if the air temperature of the air conditioning duct is higher than the target value, the cooling capacity is too little at this time, and the cooling capacity needs to be increased. The diverter valve is adjusted to reduce the amount of air flowing to the right to lower the air temperature; When the difference between the outside temperature and the target temperature is large, the refrigeration cycle needs to be turned on, and the air flows into the channels on both sides through the diverter valve according to demand; When the air flows through the left side, the air temperature is lowered to a certain temperature and mixed with the air flowing through the refrigeration cycle to reach the target temperature; the temperature of the air flowing into the vehicle is monitored based on the air duct temperature sensor: when the temperature of the air duct temperature sensor is lower than the preset temperature range, it is necessary to reduce the power of the compressor, reduce the cooling capacity, and increase the temperature of the air in the air duct; when the temperature of the air duct temperature sensor is in the preset temperature range, no additional operation is required; when the temperature of the air duct temperature sensor is higher than the preset temperature range, it is necessary to increase the power of the compressor to increase the cooling capacity.

5. The automobile air conditioning system based on liquid ammonia cooling energy according to claim 2, characterized in that: When the passenger turns on the air conditioner and selects the heating mode, the valve from the cooling water of the ammonia engine to the warm air heat exchanger needs to be opened to allow the air to flow through the warm air heat exchanger. The air then flows in two directions, one direction directly into the car, and the other direction to the liquid ammonia evaporator. The air then flows into the outside or inside of the car according to the situation. When the difference between the outside temperature and the target temperature is small, part of the air flowing through the liquid ammonia evaporator is discharged outside the vehicle according to demand, and part of it enters the air conditioning duct and mixes with the hot air to reduce the air temperature in the air conditioning duct and maintain the air conditioning duct temperature within the target range; If the air from the liquid ammonia evaporator box is fully passed into the air conditioning duct, and the temperature of the duct temperature sensor is still higher than the upper limit of the preset temperature range, the cooling capacity of the liquid ammonia evaporation is not enough to lower the air temperature to the target temperature. It is necessary to pass part of the air into the right flow direction, and do not start the refrigeration cycle first, and rely on cold air for cooling. If it still cannot meet the demand, start the refrigeration cycle, and rely on the refrigeration cycle to increase the cooling capacity to lower the air temperature to the target range; when the temperature of the air duct temperature sensor is in the preset temperature range, no additional operation is required; when the temperature of the air duct temperature sensor is lower than the preset temperature range, the cooling capacity of the refrigeration cycle is reduced first, then the amount of cold air is reduced, and finally the cooling capacity of the liquid ammonia is reduced, so as to maintain the temperature within the target range; When the difference between the outside temperature and the target temperature is large, and when the temperature of the air duct temperature sensor is higher than the preset temperature range, it means that the amount of cold air is too small, and the amount of cold liquid ammonia flowing into the air conditioning duct needs to be increased to maintain the temperature within the target range; when the temperature of the air duct temperature sensor is within the preset temperature range, it means that the working condition is good and no additional operation is required; when the temperature of the air duct temperature sensor is lower than the preset temperature range, it means that the amount of cold air is too large, and the amount of cold liquid ammonia flowing into the air conditioning duct needs to be reduced to maintain the temperature within the target range.

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