An automobile air-conditioning system based on liquid ammonia cooling energy

Abstract

The present invention is applicable to the technical field of automotive air conditioning systems and provides an automotive air conditioning system based on liquid ammonia cooling energy. The system comprises an ammonia engine unit, an air conditioning unit, and an air distribution unit. The air distribution unit includes a blower connected to a warm air heat exchanger and an evaporator, respectively, via a diverter valve. The warm air heat exchanger is connected to a liquid ammonia evaporator tank and delivers gas to the exterior of the vehicle through the tank. The warm air heat exchanger is also directly connected to the interior of the vehicle via an air conditioning duct, which is also equipped with an air duct temperature sensor. This system utilizes the cooling energy of liquid ammonia evaporation, reducing the operating requirements of the air conditioner and effectively reducing energy losses in the ammonia engine. The system also utilizes the waste heat of the ammonia engine to maintain the temperature of the liquid ammonia evaporator tank, effectively preventing overcooling of the liquid ammonia evaporator tank from affecting evaporation efficiency, ensuring stable operation of the ammonia engine and reducing the energy required to maintain the temperature of the liquid ammonia evaporator tank.

Description

Technical Field

[0001] The present 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 significant portion of total transportation emissions, making the green transformation of internal combustion engines a key focus. Energy conservation, emission reduction, and efficient energy utilization will be key themes for a long time to come. Ammonia, with its carbon-free fuel and carbon dioxide-free combustion, boasts a high energy density and is considered one of the most promising fuels for internal combustion engines. Furthermore, ammonia storage and transportation technology is well-established, and vehicles typically store it in liquid form.

[0003] The conversion of liquid ammonia into gaseous ammonia is a physical process of vaporization and heat absorption. Furthermore, since ammonia engines continuously require ammonia during operation, this heat absorption process occurs continuously. While air convection during vehicle operation removes some of the cooling energy, it can still easily cause the liquid ammonia evaporator to cool or even freeze, thus affecting its evaporation efficiency.

[0004] Car air conditioners are energy-intensive accessories, accounting for 10%-20% of a vehicle's energy consumption, half of which is used to drive the refrigeration compressor. The commonly used refrigerant is R134a, which has a latent heat of vaporization of 215 kJ / kg. In ammonia engines, since ammonia is used as fuel, liquid ammonia evaporates continuously. Furthermore, its latent heat of vaporization is 1369 kJ / kg, approximately seven times that of R134a, making it an excellent refrigerant. Currently, liquid ammonia is primarily used as a refrigerant in cold storage, with some success in industry. While some researchers have studied the utilization of cold energy in marine ammonia engines, the system's complexity makes it impractical for automotive application, and there is currently a lack of relevant research specifically for automotive applications. 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 includes an ammonia tank, a liquid ammonia evaporation tank, and an ammonia engine. The liquid ammonia evaporation tank and the ammonia engine are both arranged on the front side of the vehicle. The ammonia tank and the liquid ammonia evaporation tank are connected by 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 by 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 includes an evaporator, a compressor, a condenser, a drying bottle and an expansion valve connected in sequence. The evaporator is provided with a second temperature sensor, the condenser is also installed with a fan and an outside temperature sensor, and a pressure sensor is further provided between the condenser and the drying bottle.

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

[0010] The liquid ammonia evaporation tank includes a liquid ammonia evaporation tank shell, in which a liquid ammonia delivery pipe and a gas delivery pipe are provided. Both the liquid ammonia delivery pipe and the gas delivery pipe are S-shaped, with the liquid ammonia delivery pipe placed horizontally and the gas delivery pipe placed vertically. A plurality of fins are further provided inside the liquid ammonia evaporation tank shell, and the first temperature sensor is mounted on the fins.

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

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

[0013] In current mode, the system's primary task is to maintain a stable fuel supply at the ammonia engine's inlet. The temperature control logic for the liquid ammonia evaporator is shown in the figure. The liquid ammonia pressure sensor and the first temperature sensor detect the liquid ammonia pressure and the temperature of the evaporator. These pressures are compared with preset temperatures and pressures. If the pressure falls below the preset pressure, the ammonia tank is deemed insufficient and refueling is necessary. If the temperature falls below the preset temperature, the evaporator is heated. The blower is turned on, and the diverter valve directs the gas solely to the left side of the gas path. The valve connecting the engine coolant to the heater heat exchanger is opened, allowing air to flow through the heater heat exchanger, heating it. The heated air then flows through the evaporator, raising the temperature and maintaining a stable temperature. Since the air conditioning system is not turned on by the passengers, excess gas is discharged directly outside the vehicle.

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

[0015] In this mode, the air conditioning unit's primary task is to meet passengers' cooling needs while preventing the liquid ammonia evaporator from freezing, which would affect evaporation efficiency. Therefore, the temperature of the liquid ammonia evaporator must be monitored and heated when necessary. The outside temperature sensor on the air conditioning unit's condenser detects the current ambient temperature and sets a target temperature based on passenger demand. The air conditioning unit's cooling demand is determined based on the temperature difference. The inside temperature sensor measures the inside temperature and compares it with the target temperature range to determine whether the operating state needs to be changed. This determines the target air temperature in the air conditioning duct. The air duct temperature sensor monitors the air duct temperature and compares it with the target range to determine whether the cooling capacity meets the demand. The control logic diagram for the air conditioning unit in cooling mode is shown in the figure.

[0016] When the outside temperature is not significantly different from the target temperature, the vehicle's cooling capacity requirements are low, and the liquid ammonia evaporator alone can handle the task. The refrigeration cycle does not need to be activated. Air flows through the diverter valve into the left passage, passes through the warm air heat exchanger, and flows through the liquid ammonia evaporator, allowing the cooled air to reach the end of the air conditioning duct and enter the vehicle interior. The temperature of the liquid ammonia evaporator determines whether the warm air heat exchanger should be activated. The ECU determines the device status based on parameters received from the ECU. If the air conditioning duct temperature is below the target, the cooling capacity is excessive, potentially causing the interior temperature to be too low or the air flow to be too cold, degrading the passenger experience. The diverter valve should be adjusted to allow outside air to enter the air conditioning duct through the right passage, where it mixes with the cooled air to achieve the target temperature. If the air conditioning duct temperature is equal to the target, the cooling capacity is adequate and no additional operation is required. If the air conditioning duct temperature is above the target, the cooling capacity is insufficient and needs to be increased. The diverter valve can be adjusted to reduce the amount of air flowing to the right side to lower the air temperature.

[0017] When the outside temperature differs significantly from the target temperature, the vehicle requires a greater cooling capacity than the liquid ammonia evaporator operating alone can provide. The refrigeration cycle must be activated, and air flows through the diverter valve, flowing into the two side channels as needed. As the air flows through the left side, its temperature is lowered to a certain level and mixed with the air flowing through the refrigeration cycle to achieve the target temperature. The air flow temperature sensor monitors the temperature of the air entering the vehicle. When the air flow temperature sensor is below the preset temperature range, the cooling capacity is excessive, requiring compressor power reduction to reduce cooling capacity and increase the air flow temperature. When the air flow temperature sensor is within the preset temperature range, the cooling capacity meets the requirements and no additional action is required. When the air flow temperature sensor is above the preset temperature range, the cooling capacity is insufficient and needs to be increased. In this case, the compressor power should be increased to increase cooling capacity.

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

[0019] In heating mode, the air conditioning unit's primary function is to provide warm air to the interior, ensuring comfort while also preventing the liquid ammonia evaporator from cooling too low. Heating mode is determined in the same way as cooling mode, using the relationship between the temperatures of various temperature sensors. The target air temperature range in the air conditioning duct is determined based on passenger demand and the outdoor temperature. This temperature is then compared with the temperature reading of the duct temperature sensor, and temperature control is achieved by adjusting airflow direction and various components.

[0020] Since the air conditioning unit is in heating mode, the valve connecting the engine coolant to the heater heat exchanger needs to be opened, allowing air to flow through the heater heat exchanger. The air then flows in two directions: one directly into the vehicle interior to heat the air inside. The other is to the liquid ammonia evaporator to prevent the liquid ammonia evaporator from cooling too low. The air is then directed to the exterior or interior of the vehicle, depending on the situation. The control logic diagram for the air conditioning unit in heating mode is shown in the figure.

[0021] When the difference between the outside temperature and the target temperature is small, the air conditioning system requires less heating capacity. However, the engine's waste heat is relatively high, and the airway temperature sensor's temperature is inevitably higher than the expected temperature range. Directly venting this air into the vehicle would reduce passenger comfort. Therefore, some cold air is introduced to cool the hot air. As needed, a portion of the air flowing through the liquid ammonia evaporator is discharged outside, while a portion is directed into the airway, where it mixes with the hot air to lower the air temperature within the airway, maintaining it within the target range. If all the air from the liquid ammonia evaporator is vented into the airway, but the airway temperature sensor's temperature is still above the upper limit of the preset temperature range, the cooling capacity of the liquid ammonia evaporation is insufficient to lower the air temperature to the target range. It is necessary to introduce some air into the right-hand flow path, initially without activating the refrigeration cycle, to rely on cold air for cooling. If this still does not meet the required temperature, activate the refrigeration cycle to increase cooling capacity and lower the air temperature to the target range. When the airway temperature sensor's temperature is within the preset temperature range, the requirements are met and no further action 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. 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 outside temperature differs significantly from the target temperature, the air conditioning unit requires more heating. In this case, less cooling capacity is needed to neutralize the heat, and the cooling capacity of liquid ammonia evaporation can meet the demand. As the outside temperature drops further, the effectiveness of air convection generated by the vehicle's movement in heating the liquid ammonia evaporator tank decreases, requiring more engine waste heat to maintain a stable temperature. If the airway temperature sensor's temperature is above the preset temperature range, it indicates insufficient cooling air flow. Increased cooling capacity from liquid ammonia is required to maintain the temperature within the target range. If the airway temperature sensor's temperature is within the preset temperature range, the unit is operating properly and no additional action is required. If the airway temperature sensor's temperature is below the preset temperature range, it indicates excessive cooling air flow. Reduced cooling capacity from liquid ammonia is required to maintain the temperature within the target range.

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

[0024] (1) By utilizing the cooling capacity of liquid ammonia evaporation, the working requirements of the air conditioner are reduced, which can effectively reduce the energy loss of the ammonia engine;

[0025] (2) It can make the refrigeration cycle design 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, effectively preventing the liquid ammonia evaporator from being overcooled and affecting the evaporation efficiency, ensuring the stable operation of the ammonia engine, and at the same time reducing the energy demand for the liquid ammonia evaporator to maintain the temperature, which 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 structural diagram 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 in 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 in cooling mode based on liquid ammonia cooling energy 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: ammonia tank 1; liquid ammonia pump 2; liquid ammonia pressure sensor 3; expansion valve 4; liquid ammonia evaporator 5; first temperature sensor 6; warm air heat exchanger 7; diverter valve 8; blower 9; evaporator 10; second temperature sensor 11; compressor 12; condenser 13; fan 14; outside temperature sensor 15; pressure sensor 16; drying bottle 17; expansion valve 18; inside the vehicle 19; inside temperature sensor 20; airway temperature sensor 21; outside the vehicle 22; pressure regulating tank 23; ammonia flowmeter 24; ammonia temperature sensor 25; ammonia engine 26; liquid ammonia delivery pipe 27; gas delivery pipe 28; fin 29; liquid ammonia evaporator housing 30. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to 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 with reference to 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 includes 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 on the front side of the vehicle. The ammonia tank 1 and the liquid ammonia evaporation tank 5 are connected by a pipeline, and a liquid ammonia pump 2, a liquid ammonia pressure sensor 3, and an expansion valve 4 are sequentially arranged on the pipeline. 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 surge tank 23, an ammonia flow meter 24, and an ammonia temperature sensor 25 are sequentially arranged on the pipeline.

[0037] The air conditioning unit includes an evaporator 10, a compressor 12, a condenser 13, a drying bottle 17 and an expansion valve 18 connected in sequence. The evaporator 10 is provided with a second temperature sensor 11. The condenser 13 is also provided with a fan 14 and an outside temperature sensor 15. A pressure sensor 16 is also provided between the condenser 13 and the drying bottle 17.

[0038] The air distribution unit includes a blower 9, which is respectively connected to the warm air heat exchanger 7 and the evaporator 10 through a diverter valve 8. The warm air heat exchanger 7 is connected to the liquid ammonia evaporation tank 5, and the gas is transported to the outside of the vehicle 22 through the liquid ammonia evaporation tank 5. The warm air heat exchanger 7 is also directly connected to the interior of the vehicle 19 through the 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 an embodiment of the present invention, the liquid ammonia evaporator 5 is combined with the automobile air conditioner. The cooling capacity of the evaporated liquid ammonia is used during cooling to reduce the power output of the engine, thereby achieving the purpose of reducing fuel consumption. At the same time, the residual heat of the engine is also used to ensure the stability of the ammonia gas when it enters 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 begin evaporation. The first temperature sensor 6 provided on the liquid ammonia evaporation tank 5 is used to determine 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 to detect the state of the ammonia at the intake end of the ammonia engine 26 and ensure the intake state of the ammonia engine 26.

[0041] In the air conditioning unit, the coolant undergoes expansion, evaporation, compression, cooling, and drying to achieve its cooling function. An outdoor temperature sensor 15 is also installed to detect the current outdoor temperature. Compared to traditional automotive air conditioning, this system utilizes liquid ammonia's cooling energy, reducing the required cooling capacity. This allows for a more compact refrigeration cycle design, saving space within the vehicle.

[0042] In the air distribution unit, air is sucked into the air duct by the blower 9, and the direction of the gas flow is controlled by the diverter valve 8. The gas is mainly divided into two directions: one is the traditional refrigeration cycle (i.e., directly delivered to the air conditioning unit), and the other is to pass the air into the warm air heat exchanger 7. The air flow direction 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 in FIG. 5 , as a preferred embodiment of the present invention, the liquid ammonia evaporation tank 5 includes a liquid ammonia evaporation tank shell 30 . A liquid ammonia delivery pipe 27 and a gas delivery pipe 28 are provided in the liquid ammonia evaporation tank shell 30 . The liquid ammonia delivery pipe 27 and the gas delivery pipe 28 are both S-shaped, with the liquid ammonia delivery pipe 27 placed horizontally and the gas delivery pipe 28 placed vertically. A plurality of fins 29 are further provided inside the liquid ammonia evaporation tank shell 30 , and the first temperature sensor 6 is mounted on the fins 29 .

[0044] In this embodiment of the present invention, liquid ammonia enters through one end of liquid ammonia delivery pipe 27, expands by absorbing heat, and becomes gaseous before flowing out the other end of liquid ammonia delivery pipe 27. During this process, the liquid ammonia exchanges heat with liquid ammonia delivery pipe 27, which in turn exchanges heat with the surrounding air through fins 29. During vehicle operation, the fins remove some heat through forced convection with the air. First temperature sensor 6 monitors the fin temperature to prevent it from falling too low. Air in the air conditioning duct enters the liquid ammonia evaporator through one end of gas delivery pipe 28, exchanges heat with fins 29, raising their temperature, and flows out through the other end of gas delivery pipe 28, then flows outside or inside the vehicle as needed.

[0045] Working Principle: This system primarily collects data through various sensors installed in various locations and transmits this data to the ECU. The ECU uses this data to determine the operating status and, in turn, controls the entire system, enabling the cooling and heating functions of the air conditioning unit and maintaining the stability of the gas at the engine inlet. The ECU determines the passenger's needs based on the selected air conditioning mode and sensor data, and controls the entire system. The specific implementation scheme is as follows:

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

[0047] In the current mode, the main task of the system is to maintain the stability of the fuel supply at the inlet 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 determined 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 is allowed to pass through the left air path through the diverter valve 8. The valve from the engine cooling water to the warm air heat exchanger 7 is opened, and the air flows through the warm air heat exchanger 7 to heat the air. The air with 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 a 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, it is necessary to monitor the temperature of the liquid ammonia evaporator 5 in this mode 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 cooling mode is as follows. Figure 4 shown.

[0050] When the difference between the outside temperature and the target temperature is not significant (the specific temperature difference range can be set based on actual conditions), the vehicle's required cooling capacity is low, and the liquid ammonia evaporator 5 can perform its function alone. The refrigeration cycle does not need to be activated. Air flows through diverter valve 8 into the left passage, passes through the warm air heat exchanger 7, and flows through the liquid ammonia evaporator 5, allowing the cooled air to reach the end of the air conditioning duct and then enter the vehicle interior 19. The temperature of the liquid ammonia evaporator 5 determines whether the warm air heat exchanger 7 needs to be activated. The device status is determined based on the parameters received by the ECU. If the air conditioning duct air temperature is below the target value, the cooling capacity is excessive, potentially causing the interior temperature to be too low or the air flow to be too cold, resulting in a poor passenger experience. Diverter valve 8 should be adjusted to allow outside air to enter the air conditioning duct through the right passage, where it mixes with the cooled air to reach the target temperature. If the air conditioning duct air temperature is equal to the target temperature, the cooling capacity is adequate 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 is reduced to lower the air temperature.

[0051] When the outside temperature differs significantly from the target temperature, the vehicle requires a high cooling capacity, which the liquid ammonia evaporator 5 alone cannot meet. The refrigeration cycle must be activated, and air flows through the diverter valve 8 into the two side channels as needed. As the air flows through the left side, the air temperature is lowered to a certain level 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 by the airway temperature sensor 21. When the temperature of the airway temperature sensor 21 is below the preset temperature range, it indicates that the cooling capacity is excessive, and the power of the compressor 12 needs to be reduced to reduce the cooling capacity and increase the temperature of the air in the airway. When the temperature of the airway temperature sensor 21 is within the preset temperature range, the cooling capacity meets the requirements and no additional operation is required. When the temperature of the airway temperature sensor 21 is above the preset temperature range, the cooling capacity is low and needs to be increased. In this case, the power of the compressor 12 needs to be increased to increase the cooling capacity.

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

[0053] In heating mode, the air conditioning unit's primary function is to provide warm air to the interior 19, ensuring a comfortable cabin environment while also preventing the liquid ammonia evaporator 5 from cooling too low. Heating mode is determined in the same manner as cooling mode, using the relationship between the temperatures of various temperature sensors. The target air temperature range within the air conditioning duct is determined based on passenger demand and the outdoor temperature. This temperature is then compared with the temperature reading of the duct temperature sensor 21, and temperature control is achieved by adjusting airflow direction and various components.

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

[0055] When the difference between the outside temperature and the target temperature is small, the required heating capacity of the air conditioner is low. At this time, the engine's waste heat is relatively high, and the temperature of the air duct temperature sensor 21 is inevitably higher than the expected temperature range. If it is directly vented into the vehicle, it will inevitably reduce passenger comfort. Therefore, some cold air is needed to cool the hot air. As needed, a portion of the air flowing through the liquid ammonia evaporator 5 is discharged outside the vehicle, and a portion is introduced into the air duct, where it mixes with the hot air to lower the air temperature inside the air duct and maintain the air duct temperature within the target range. If all the air from the liquid ammonia evaporator 5 is vented into the air duct, and the temperature of the air duct temperature sensor 21 is still higher than the upper limit of the preset temperature range, the cooling capacity of the liquid ammonia evaporation is insufficient to lower the air temperature to the target temperature. It is necessary to vent some air to the right side of the flow path, not initially activating the refrigeration cycle, and rely on the cold air for cooling. If this still cannot meet the requirements, the refrigeration cycle is activated, relying on the refrigeration cycle to increase the cooling capacity and lower the air temperature to the target range. When the temperature of the air duct temperature sensor 21 is within the preset temperature range, it means that the requirements are met 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. According to the order of first reducing the cooling capacity of the refrigeration cycle, then reducing the amount of cold air, and finally reducing the liquid ammonia cooling capacity, the cooling capacity is reduced to keep the temperature within the target range.

[0056] When the difference between the outside temperature and the target temperature is large, the amount of heating required by the air conditioning unit is large. At this time, the cooling capacity required to neutralize the heat is small, and the cooling capacity of liquid ammonia evaporation can meet the demand. As the ambient temperature outside the vehicle further decreases, the effect of using the air convection generated by the vehicle's movement to heat the liquid ammonia evaporator 5 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 air duct 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 cooling capacity of liquid ammonia needs to be increased to flow into the air conditioning air duct to keep the temperature within the target range. When the temperature of the air duct temperature sensor 21 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 air duct temperature sensor 21 is lower than the preset temperature range, it means that the amount of cold air is too large at this time, and the cooling capacity of liquid ammonia needs to be reduced to flow into the air conditioning air duct to keep the temperature within the target range.

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

[0058] Ammonia engine 26 requires different amounts of ammonia under different operating conditions. These are categorized as idle, low- to medium-load, high-load, full-load, acceleration, and deceleration. The first four differ in ammonia flow rate, which remains relatively constant. During acceleration, ammonia demand increases to meet acceleration requirements, while during deceleration, it decreases. Furthermore, changes in ammonia flow rate also affect the cooling capacity of the liquid ammonia evaporator.

[0059] When the air conditioning unit is running, the engine operating condition is determined by the ammonia flowmeter 24. Stable cooling capacity is key to maintaining system stability during air conditioning operation. Therefore, for the first four operating conditions, the primary impact is the heat absorbed by the evaporation of liquid ammonia during use, which is a stable state. By combining the cooling capacity corresponding to different ammonia flow rates with the aforementioned strategies, system stability can be easily maintained.

[0060] Under accelerated conditions, ammonia flow demand increases. This increases the amount of heat absorbed by the evaporating liquid ammonia, potentially causing the temperature of the liquid ammonia evaporator 5 to drop too low, affecting evaporation efficiency. In this case, the temperature of the first temperature sensor 6 on the liquid ammonia evaporator 5 is compared with a preset temperature to determine whether heating mode is necessary.

[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 scope of protection 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 includes an ammonia tank, a liquid ammonia evaporation tank, and an ammonia engine. The liquid ammonia evaporation tank and the ammonia engine are both arranged on the front side of the vehicle. The ammonia tank and the liquid ammonia evaporation tank are connected by 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 by 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 includes an evaporator, a compressor, a condenser, a drying bottle and an expansion valve connected in sequence. The evaporator is provided with a second temperature sensor, the condenser is also installed with a fan and an outside temperature sensor, and a pressure sensor is further provided between the condenser and the drying bottle. The air distribution unit includes a blower, which is respectively connected to the warm air heat exchanger and the evaporator through a diverter valve. The warm air heat exchanger is connected to the liquid ammonia evaporator and transports the gas to the outside of the vehicle through the liquid ammonia evaporator. The warm air heat exchanger is also directly connected to the interior of the vehicle through the air-conditioning air duct, and an air duct temperature sensor is also provided at the air-conditioning air duct. An interior 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 tank includes a liquid ammonia evaporation tank shell, in which a liquid ammonia delivery pipe and a gas delivery pipe are provided. Both the liquid ammonia delivery pipe and the gas delivery pipe are S-shaped, with the liquid ammonia delivery pipe placed horizontally and the gas delivery pipe placed vertically. A plurality of fins are further provided inside the liquid ammonia evaporation tank shell, and the first temperature sensor is mounted 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 liquid ammonia pressure 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 determined that the amount of ammonia in the tank is insufficient and fuel needs to be replenished immediately; if the temperature is lower than the preset temperature, the liquid ammonia evaporator needs to be heated, the blower is turned on, and the gas is allowed to pass through the left air 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 to increase the temperature of the liquid ammonia evaporator and keep the temperature stable. 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 a passenger turns on the air conditioning unit and selects cooling mode, the outside temperature sensor on the condenser of the air conditioning unit detects the ambient temperature outside the vehicle at that time, and sets a target temperature based on the passenger's needs. The cooling demand of the air conditioning unit at that time is determined based on the temperature difference. The inside temperature sensor 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 that time, thereby determining the target temperature of the air in the air conditioning duct. The air duct temperature sensor monitors the air temperature of the air conditioning duct and compares it with the target temperature range to determine whether the cooling capacity at that time meets the demand. When the absolute value of the difference between the outside temperature and the target temperature is less than the set value, the vehicle's required cooling capacity is small, and the liquid ammonia evaporator can complete the task 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; based on the temperature of the liquid ammonia evaporator, it is determined whether the warm air heat exchanger needs to be turned on. At this time, the device status is determined by the parameters received by the ECU: if the air temperature in the air conditioning duct is lower than the target temperature range, the cooling capacity is excessive, and the diverter valve is adjusted to allow outside air to enter the air conditioning duct through the right channel and mix with the cooled air to achieve the target temperature; if the air temperature in the air conditioning duct is within the target temperature range, the cooling capacity is just right and no additional operation is required; if the air temperature in the air conditioning duct is higher than the target temperature range, the cooling capacity is insufficient and needs to be increased. By adjusting the diverter valve, the amount of air flowing to the right is reduced to lower the air temperature; When the absolute value of the difference between the outside temperature and the target temperature is greater than the set value, the refrigeration cycle needs to be turned on, and the air passes through the diverter valve and flows into the channels on both sides 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 target 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 within the target temperature range, no additional operation is required; when the temperature of the air duct temperature sensor is higher than the target 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 is directly into the car, and the other direction is the liquid ammonia evaporator. The air is then selected to be ventilated outside or inside the car according to the situation. When the absolute value of the difference between the outside temperature and the target temperature is less than the set value, the air flowing through the liquid ammonia evaporator is partially discharged to the outside of the vehicle and partially enters the air conditioning duct to mix with the hot air, thereby lowering the air temperature in the air conditioning duct and maintaining the air conditioning duct temperature within the target temperature range; If all the air from the liquid ammonia evaporator is passed into the air conditioning duct, and the temperature of the air duct temperature sensor is still higher than the upper limit of the target temperature range, the cooling capacity of the liquid ammonia evaporation is insufficient 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 temperature range; when the temperature of the air duct temperature sensor is within the target temperature range, no additional operation is required; when the temperature of the air duct temperature sensor is lower than the target temperature range, reduce the cooling capacity of the refrigeration cycle first, then reduce the amount of cold air, and finally reduce the cooling capacity of the liquid ammonia, so as to reduce the cooling capacity and maintain the temperature within the target temperature range; When the absolute value of the difference between the outside temperature and the target temperature is greater than the set value, and when the temperature of the air duct temperature sensor is higher than the target temperature range, it means that the amount of cold air is too small, and the cooling capacity of liquid ammonia needs to be increased to flow into the air-conditioning duct to maintain the temperature within the target temperature range; when the temperature of the air duct temperature sensor is within the target 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 target temperature range, it means that the amount of cold air is too large, and the cooling capacity of liquid ammonia needs to be reduced to flow into the air-conditioning duct to maintain the temperature within the target temperature range.

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