An exhaust heat recovery air conditioning system with mode adjustment

Abstract

The present invention discloses an exhaust heat recovery air conditioning system with mode adjustment, which includes nine modes, namely: precooling and reheating mode, precooling and reheating bypass mode, precooling and reheating supplementary heating mode, surface cooler antifreeze mode, recovery coil antifreeze mode, preheating supplementary heating mode, preheating and reheating mode, precooling mode and standby mode. The present invention enables the air conditioning system to automatically adjust the working mode, saves manual operation, and greatly improves the operating efficiency; in addition, the working mode of the air conditioning system is subdivided into 9 types and adjusted accordingly, the adjustment process is smooth, the mode switching is accurate, and the problem of insufficient energy saving during actual operation is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of heat recovery, and in particular to an exhaust heat recovery air conditioning system with mode adjustment. Background Art

[0002] In the air conditioning system, in order to maintain the balance of indoor air volume, the amount of fresh air sent into the room and the amount of exhaust air discharged to the outside should be kept equal. The fresh air entering from the outside can only be sent into the room after being processed by some air conditioning sections (cooling, humidification, heating, etc.) to a suitable state, and the indoor air finally reaches the designed state point. In this way, there is a kind of energy consumption between the fresh air and the exhaust air, which is generally called the fresh air load. The larger the fresh air volume, the more air needs to be processed, and the greater the fresh air load. The fresh air load generally accounts for a large proportion. For conventional air conditioning systems, the exhaust air is directly discharged to the outside without being processed, and as a result, this part of the energy is wasted. If we use the exhaust air to process the fresh air (precooling or preheating) through the heat exchanger and recover some fresh air energy consumption from the exhaust air, we can reduce the fresh air load and thus reduce the total energy consumption of the air conditioner.

[0003] Working principle of conventional exhaust heat recovery air conditioning system: part of the air coming out of the air-conditioned room is exchanged with the fresh air through the heat recovery device, so as to pre-treat the fresh air. The exhaust air after heat exchange is discharged in the form of waste gas. The pre-treated fresh air is mixed with the return air and then processed to the supply air state and sent into the room. Most of the time, the energy recovered from the return air is not enough to process the fresh air to the supply air state point, and then the air needs to be reprocessed. If the temperature difference between indoor and outdoor is small, there is no need to use exhaust heat recovery. Therefore, a bypass duct is set at the entrance of the fresh air, which is opened in the transition season.

[0004] There are three main types of heat recovery for air-conditioning systems on the market: plate type, rotary type and heat pipe type.

[0005] The common problems of the above three types of heat recovery equipment are: large size, high energy consumption, unstable operation, all of which are passive recovery and cannot adapt to changes in seasons and working conditions. They may even have adverse effects and are not energy-efficient enough. In addition, manual intervention is often required during the operation of the air-conditioning system to make corresponding adjustments. The process is relatively complicated and may introduce new manual operation problems, affecting the accurate operation of the air-conditioning working mode. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to propose an exhaust heat recovery air-conditioning system with mode adjustment, so that the air-conditioning system can automatically adjust the working mode, solving the problems of passive recovery and the need for manual intervention; in addition, the working mode of the air-conditioning system is subdivided into 9 types for corresponding adjustments, which effectively solves the problem that the actual working mode is not energy-efficient enough.

[0007] The specific technical solutions adopted are as follows:

[0008] A heat recovery air conditioner system with mode adjustment uses a first bypass valve 10, a second bypass valve 14, a two-way control valve 15, a three-way control valve 16, a heat recovery plate heat exchanger valve 12, a heat recovery control valve 9, and a circulation water pump 11 for adjustment. This heat recovery air conditioner system includes nine modes, namely: pre-cooling and reheating mode, pre-cooling and reheating bypass mode, pre-cooling and reheating heat supplement mode, surface cooler anti-freezing mode, recovery coil anti-freezing mode, preheating and heat supplement mode, preheating and reheating mode, pre-cooling mode, and standby mode. The mode adjustment method is as follows: Input the set supply air temperature TT24, supply air humidity HT24, and flow rate into the heat recovery air conditioner system. At the same time, input the outdoor air temperature TT20 and outdoor air humidity HT20 into the heat recovery air conditioner system. Denote the return air reheating energy as TT23, the energy in the reheating pipeline as T27, the energy in the recovery pipeline as TT29, the air temperature passing through the preheater as T21, and the return water temperature of the ethylene glycol liquid in the preheater as TT27. When HT20 > HT24 outdoors, judge whether TT23 > TT24 is satisfied. If it is satisfied, enter the pre-cooling and reheating mode, close the first bypass valve 10, the second bypass valve 14, and the heat recovery plate heat exchanger valve 12, and open the heat recovery control valve 9, the two-way control valve 15, and the three-way control valve 16. If it is not satisfied, continue to judge whether T27 < TT29 is met. If it is met, enter the pre-cooling and reheating bypass mode, close the second bypass valve 14 and the heat recovery plate heat exchanger valve 12, and open the first bypass valve 10, the heat recovery control valve 9, the two-way control valve 15, and the three-way control valve 16. If it is not met, enter the pre-cooling and reheating heat supplement mode, close the first bypass valve 10 and the second bypass valve 14, and open the heat recovery plate heat exchanger valve 12, the two-way control valve 15, and the three-way control valve 16. When HT20 ≤ HT24, judge whether it belongs to the case of TT20 ≤ TT24. If it does, continue to judge whether T21 is less than 0°C. If it is less, redistribute the reheater energy and enter the surface cooler anti-freezing mode, close the first bypass valve 10, the second bypass valve 14, and the heat recovery plate heat exchanger valve 12, and open the heat recovery control valve 9, the two-way control valve 15, and the three-way control valve 16. If it is not less, judge whether TT27 < -2°C is satisfied. If it is satisfied, enter the recovery coil anti-freezing mode, close the first bypass valve 10, the three-way control valve 16, and the heat recovery plate heat exchanger valve 12, and open the second bypass valve 14, the heat recovery control valve 9, and the two-way control valve 15. If it is not satisfied, judge whether the ethylene glycol liquid has enough heat to heat the air to the supply air temperature TT24. If it does, enter the preheating and reheating mode. If not, enter the preheating and heat supplement mode, open the heat supplement plate, the heat recovery plate heat exchanger valve 12, the heat recovery control valve 9, the two-way control valve 15, and the three-way control valve 16, and close the first bypass valve 10 and the second bypass valve 14;If not, input the reheat set temperature TT29set of ethylene glycol, and determine whether it meets the condition of TT29 < TT29set. If it meets, enter the precooling mode, close the first bypass valve 10, the second bypass valve 14, the supplementary heat exchanger valve 12, and the three-way control valve 16, open the heat recovery control valve 9 and the two-way control valve 15. If it does not meet, enter the standby mode, close the first bypass valve 10, the second bypass valve 14, the supplementary heat exchanger valve 12, the heat recovery control valve 9, the two-way control valve 15, and the three-way control valve 16, and stop the circulation pump 11.

[0009] By using multiple judgments of detailed temperature and humidity, accurately identify the most suitable current operating mode of the air conditioning system, which can be automatically adjusted according to seasons and working conditions without manual intervention, greatly improving the operating efficiency of the air conditioning system.

[0010] Preferably, a plurality of temperature sensors are arranged on the air handling unit 18 and the pipeline 17 in the air conditioning system. By using the plurality of temperature sensors, a plurality of temperature data are obtained, which is convenient for adjusting the mode based on these data.

[0011] Preferably, in the air conditioning system, a first temperature and humidity sensor 20 is provided at the front end of the preheating coil 1, a first temperature sensor 21 is provided at the front end of the cooling coil 2, a second temperature sensor 22 is provided at the front end of the reheat recovery coil 3, a third temperature sensor 23 is provided at the front end of the humidifier 4, a second temperature and humidity sensor 24 is provided at the rear end of the supply air fan 5, a third temperature and humidity sensor 25 is provided at the front end of the heat recovery coil 7, and a fourth temperature sensor 26 is provided at the rear end of the heat recovery coil 7. By using the plurality of temperature and humidity sensors to transmit the temperature and humidity required by the air conditioning system in a timely manner, it is convenient for the air conditioning system to carry out adjustment work and reduce energy consumption.

[0012] Preferably, when the outdoor air humidity HT20 > the supply air temperature HT24, the air conditioning system judges whether the return air reheat energy carried by the ethylene glycol liquid after heat recovery through the heat recovery coil 7 can heat the air to the supply air temperature TT24 according to the data transmitted by the seventh temperature sensor 29 at the rear end of the heat recovery control valve 9. If it can, turn on the precooling and reheat mode, open the three-way control valve 16, let the ethylene glycol liquid flow into the reheat recovery coil 3, and at the same time control the two-way control valve 15 to adjust the flow rate of the ethylene glycol liquid entering the reheat coil to control the air heating temperature.

[0013] Preferably, when the outdoor air humidity HT20 > the supply air temperature HT24, dehumidify through the cooling coil 2 in the air conditioning system to reduce the fresh air received by the air conditioning system to the dew point temperature. When the outdoor air humidity HT20 > the supply air temperature HT24, the air humidity in the current environment is too high, and it is necessary to use the cooling coil 2 to dehumidify the fresh air and reduce the air temperature to the dew point temperature.

[0014] Preferably, the air conditioning system is arranged in the room 6, a group of preheating coils 1 are placed in front of the surface cooling coils 2 in the air-conditioning system, a group of heat recovery coils 7 are placed in front of the exhaust fan 8, the inlet of the reheat recovery coil 3 is connected to the outlet of the heat recovery coil 7, the outlet of the reheat recovery coil 3 is connected to the inlet of the preheating coil 1, and the outlet of the preheating coil 1 is connected to the inlet of the heat recovery coil 7, so as to complete the circulation; a circulating water pump 11 is installed on the pipeline between the heat recovery coil 7 and the reheat recovery coil 3, and a heat supplement plate exchanger 13 is installed after the circulating water pump 11; a two-way control valve 15 is installed before the inlet of the reheat recovery coil 3, a heat recovery control valve 9 is installed after the outlet of the heat recovery coil 7, a three-way control valve 16 is installed at the outlet of the reheat recovery coil 3, a second bypass valve 14 is installed before the circulating water pump 11, and a first bypass valve 10 is installed after the heat supplement plate exchanger 13. Setting an effective heat recovery process can further save energy in the air conditioning system.

[0015] Preferably, the first bypass valve 10, the circulating water pump 11, the heat supplement plate exchanger 13, the heat supplement plate exchanger valve 12 and the second bypass valve 14 form a hydraulic control unit, which receives signals from multiple temperature sensors arranged on the air conditioning box 18 and the pipeline 17 in the air conditioning system, and controls the valve opening and closing according to the signals from the multiple temperature sensors. The hydraulic control unit can effectively open and close the valve to achieve mode adjustment of the air conditioning system.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In the technical solution of the present invention, the air-conditioning system can automatically adjust the working mode, which solves the problem of passive recovery and the need for manual intervention of the air-conditioning system in the prior art; in addition, the working mode of the air-conditioning system is subdivided into 9 types and adjusted accordingly. The adjustment process is smooth and the mode switching is accurate, which effectively solves the problem that the actual working mode is not energy-efficient enough. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of a method for regulating an exhaust heat recovery air conditioning system with mode regulation;

[0019] Figure 2 The schematic diagram of the structure is an exhaust heat recovery air conditioning system with mode adjustment.

[0020] Description of reference numerals:

[0021] 1. Preheating coil, 2. Surface cooling coil, 3. Reheat recovery coil, 4. Humidifier, 5. Supply air fan, 6. Room, 7. Heat recovery coil, 8. Exhaust fan, 9. Heat recovery control valve, 10. First bypass valve, 11. Circulating water pump, 12. Heat supplement plate exchange valve, 13. Heat supplement plate exchange, 14. Second bypass valve, 15. Two-way control valve, 16. Three-way control valve, 17. Pipeline, 18. Air conditioning box, 19. Hydraulic control unit, 20. First temperature and humidity sensor, 21. First temperature sensor, 22. Second temperature sensor, 23. Third temperature sensor, 24. Second temperature and humidity sensor, 25. Third temperature and humidity sensor, 26. Fourth temperature sensor, 27. Fifth temperature sensor, 28. Sixth temperature sensor, 29. Seventh temperature sensor. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1 and attached Figure 2 The present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example

[0023] like Figure 1 As shown, it is a flow chart of a method for adjusting an exhaust heat recovery air conditioning system with mode adjustment, which makes detailed judgments on the humidity, temperature and heat data in the air conditioning system, and adjusts the corresponding 9 working modes to make the air conditioning system work in the best state, wherein Y indicates that the judgment conditions are met, and N indicates that the judgment conditions are not met.

[0024] Figure 2As shown, it is a structural schematic diagram of an exhaust heat recovery air-conditioning system with mode adjustment. The mode adjustment of the air-conditioning system in this embodiment is explained by taking this structure as an example, specifically: the outlet of the preheating coil 1 is connected to the surface cooling coil 2, the outlet of the surface cooling coil 2 is connected to the reheat recovery coil 3, the outlet of the reheat recovery coil 3 is connected to the humidifier 4, the outlet of the humidifier 4 is connected to the air supply fan 5, the outlet of the air supply fan 5 is connected to the room 6, the room 6 is connected to the heat recovery coil 7, the outlet of the heat recovery coil 7 is connected to the exhaust fan 8, the tube coil outlet of the heat recovery coil 7 is connected to the circulating water pump 11, the outlet of the circulating water pump 11 is connected to the supplementary heat plate exchanger 13, the outlet of the supplementary heat plate exchanger 13 is connected to the tube coil inlet of the reheat recovery coil 3 and the tube coil inlet of the preheating coil 1, the tube coil outlet of the reheat recovery coil 3 is connected to the tube coil inlet of the preheating coil 1, and the tube coil outlet of the preheating coil 1 is connected to the heat recovery coil The heat recovery coil 7 is connected to the tube coil inlet to complete the circulation; a circulating water pump 11 is installed on the pipeline between the heat recovery coil 7 and the reheat recovery coil 3, and a supplementary heat plate exchanger 13 is installed behind the circulating water pump 11; a supplementary heat plate exchanger valve 12 is set on the hot water side outlet pipeline of the supplementary heat plate exchanger 13, a two-way control valve 15 is installed before the inlet of the reheat recovery coil 3, a heat recovery control valve 9 is installed after the outlet of the heat recovery coil 7, a three-way control valve 16 is installed at the outlet of the reheat recovery coil 3, a second bypass valve 14 for winter antifreeze is installed before the circulating water pump 11, and a first bypass valve 10 for inputting fresh air in summer is installed behind the supplementary heat plate exchanger 13.

[0025] A plurality of temperature sensors are arranged on the air conditioning box 18 and the pipeline 17, specifically: a first temperature and humidity sensor 20 is arranged at the front end of the preheating coil 1 on the air conditioning box 18, for obtaining the temperature and humidity data of the fresh air; a first temperature sensor 21 is arranged at the front end of the surface cooling coil 2, for obtaining the temperature of the fresh air preheated by the preheating coil 1; a second temperature sensor 22 is arranged at the front end of the reheat recovery coil 3, for monitoring the cooling effect of the surface cooling coil 2 on the fresh air, to ensure that the air is reduced to the dew point temperature; a third temperature sensor 23 is arranged at the front end of the humidifier 4, for obtaining the temperature of the fresh air after passing through the reheat recovery coil 3 and mixing with the ethylene glycol liquid; a second temperature and humidity sensor 24 is arranged at the rear end of the air supply fan 5, for obtaining the actual supply air temperature; a third temperature and humidity sensor 25 is arranged at the front end of the heat recovery coil 7 , used to obtain data on the temperature and humidity of the indoor air; a fourth temperature sensor 26 is set at the rear end of the heat recovery coil 7 to obtain the temperature of the indoor air after heat recovery; a fifth temperature sensor 27 is set on the pipe 17 between the outlet of the preheating coil 1 and the inlet of the heat recovery coil 7, a sixth temperature sensor 28 is set on the pipe 17 between the outlet of the reheat recovery coil 3 and the inlet of the preheating coil 1, and a seventh temperature sensor 29 is set on the pipe 17 between the inlet of the reheat recovery coil 3 and the outlet of the heat recovery coil 7. The fifth temperature sensor 27, the sixth temperature sensor 28, and the seventh temperature sensor 29 are coupled with the hydraulic control unit of the air-conditioning system, so as to correspondingly control the flow rate of the ethylene glycol liquid at the preheating coil 1, the reheat recovery coil 3 and the heat recovery coil 7.

[0026] The hydraulic control unit includes a first bypass valve 10, a circulating water pump 11, a heat supplement plate exchanger 13, a heat supplement plate exchanger valve 12 and a second bypass valve 14. The hydraulic control unit receives signals from multiple temperature sensors arranged on the air-conditioning box 18 and the pipeline 17 in the air-conditioning system, controls the valve switch according to the signals of the multiple temperature sensors, thereby adjusting the flow of the input ethylene glycol liquid, and provides feedback based on the fifth temperature sensor 27, the sixth temperature sensor 28, and the seventh temperature sensor 29 to achieve accurate regulation of the flow.

[0027] It should be noted that the dew point temperature of fresh air refers to the temperature when the fresh air is cooled to saturation while keeping the water vapor content and air pressure of the fresh air unchanged. That is, the temperature when the water vapor in the fresh air begins to condense into dewdrops is the dew point temperature.

[0028] Ethylene glycol liquid plays multiple roles in this air conditioning system. In low temperature environment, the input of ethylene glycol liquid can lower the freezing point of water, prevent the air conditioning system from freezing, avoid problems such as pipe blockage and rupture, and ensure the normal operation of the air conditioning system; in high temperature environment, the input of ethylene glycol liquid at the preheating coil 1, the reheat recovery coil 3 and the heat recovery coil 7 can absorb part of the heat in the air and water vapor, and achieve a cooling effect; when heating is required, the ethylene glycol liquid will also release the absorbed heat in the corresponding exhaust link to increase the indoor temperature; in addition, the ethylene glycol liquid can also adjust the moisture content in the fresh air or exhaust air, thereby adjusting the air humidity.

[0029] The mode adjustment method of the exhaust heat recovery air conditioning system of this embodiment is:

[0030] In the exhaust heat recovery air conditioning system, the set supply air temperature TT24, supply air humidity HT24 and flow rate are input, and the outdoor air temperature TT20 and outdoor air humidity HT20 are obtained by setting a first temperature and humidity sensor 20 at the front end of the preheating coil 1.

[0031] The system determines whether the outdoor air humidity HT20 is greater than the set supply air humidity HT24. If the outdoor air humidity HT20 is greater than the set supply air humidity HT24, that is, the air humidity is too high in the current environment, and the exhaust heat recovery air conditioning system needs to dehumidify the fresh air, then the air temperature needs to be reduced to the dew point temperature through the surface cooling coil 2 to achieve the dehumidification function.

[0032] Then, determine whether the reheating energy of the return air transmitted indoors at the heat recovery coil 7 is sufficient to heat the fresh air at the preheating coil 1 to the set supply air temperature, that is, determine whether the reheated air temperature TT23 monitored by the third temperature sensor 23 is greater than the set supply air temperature TT24; if the return air reheating energy is sufficient to heat the air to the set supply air temperature, that is, TT23>TT24, then enter the precooling and reheating mode, and cool and reheat the fresh air in turn; at this time, the first bypass valve 10 and the second bypass valve 14 in the system are both closed, the heat supplement plate valve 12 is closed, the heat recovery control valve 9 is opened, and the two-way control valve 15 and the three-way control valve 16 are opened.

[0033] If the outdoor air humidity HT20 is greater than the set supply air humidity HT24, and if the reheating energy of the return air is not sufficient to heat the air to the set supply air temperature, i.e., TT23 < TT24, then it is further determined whether the energy in the reheating pipe is less than the energy in the recovery pipe, that is, it is determined whether the reheating pipe temperature TT27 monitored by the fifth temperature sensor 27 is less than the recovery pipe temperature TT29 monitored by the seventh temperature sensor 29. If the energy in the reheating pipe is less than the energy in the recovery pipe, i.e., TT27 < TT29, then enter the pre-cooling and reheating bypass mode, cool and reheat the fresh air, and transfer the energy in the recovery pipe to the reheating pipe to further heat the fresh air; at this time, the second bypass valve 14 in the system is closed, the heat compensation plate heat exchanger valve 12 is closed, the first bypass valve 10 is opened, the heat recovery control valve 9 is opened, the two-way control valve 15 and the three-way control valve 16 are opened.

[0034] The heat compensation plate heat exchanger 13 is a plate heat exchanger for supplementing heat, which is an efficient and compact heat exchange device. It is composed of multiple metal plates, and there are narrow channels between the multiple metal plates, which can enable the hot fluid and the cold fluid to exchange heat in the channels.

[0035] If the energy in the reheating pipe is greater than the energy in the recovery pipe, TT27 is greater than TT29, then enter the pre-cooling and reheating heat compensation mode, cool and reheat the fresh air, and use the energy in the reheating pipe for heat compensation; at this time, both the first bypass valve 10 and the second bypass valve 14 in the system are closed, the heat compensation plate heat exchanger valve 12 is opened, the heat recovery control valve 9 is opened, the two-way control valve 15 and the three-way control valve 16 are opened.

[0036] If the outdoor air humidity HT20 is less than the set supply air humidity HT24, i.e., HT20 < HT24, then it is further determined whether the outdoor air temperature TT20 is less than or equal to the set supply air temperature TT24; when the outdoor air temperature TT20 is less than or equal to the set supply air temperature TT24, i.e., TT20 ≤ TT24, it is further determined whether the air temperature TT21 passing through the preheating coil is greater than 0°C. If the air temperature TT21 passing through the preheating coil is less than 0°C, i.e., TT201 < 0°C; then by closing the three-way control valve 16, redistribute the energy of the reheater and enter the surface cooler anti-freezing mode to prevent the surface cooling coil 2 from being frozen and damaged; at this time, both the first bypass valve 10 and the second bypass valve 14 in the system are closed, the heat compensation plate heat exchanger valve 12 is closed, the heat recovery control valve 9 is opened, the two-way control valve 15 and the three-way control valve 16 are opened.

[0037] The redistribution of the reheater energy is specifically as follows: under normal operating conditions, the three-way control valve 16 is open, and the liquid in the pipeline can flow into the reheating coil 3. When it is determined that the surface cooler anti-freezing mode is to be entered, the three-way control valve 16 is closed to cancel the heat exchange of the reheating coil 3, so that all the energy directly enters the preheating coil 1. This process is the redistribution of the reheater energy.

[0038] If the air temperature TT21 passing through the preheating coil is greater than 0°C, that is, TT21>0°C; then determine whether the preheating pipe temperature TT27 is greater than -2°C, that is, determine whether TT27>-2°C; if the preheating pipe temperature TT27 is less than -2°C, the second bypass valve 14 is opened, ethylene glycol liquid is introduced, and the recovery coil antifreeze mode is entered to prevent the reheat recovery coil 3 from being damaged by freezing; at this time, the first bypass valve 10 is closed, the heat recovery plate valve 12 is closed, the second bypass valve 14 is opened, the heat recovery control valve 9 is opened, the two-way control valve 15 is opened, and the three-way control valve 16 is closed.

[0039] If the preheating pipe temperature TT27 is greater than -2°C, then determine whether the ethylene glycol in the pipe has enough heat to heat the air temperature to the set air supply temperature. If the ethylene glycol in the pipe does not have enough heat to heat the air to the set air supply temperature, that is, TT23<TT24, then open the supplementary heat plate 13 to enter the preheating and supplementary heat mode; at this time, the first bypass valve 10 and the second bypass valve 14 are closed, the supplementary heat plate valve 12 is opened, the heat recovery control valve 9 is opened, and the two-way control valve 15 and the three-way control valve 16 are opened. If the ethylene glycol in the pipe has enough heat to heat the air to the set air supply temperature, that is, TT23>TT24, then enter the preheating and reheating mode, and adjust the two-way control valve 15 until the air reaches the set air supply temperature.

[0040] When the outdoor air temperature TT20 is greater than the set supply air temperature TT24, that is, TT20>TT24, the environment at this time is in a dry and hot air state. It is necessary to recalculate a glycol reheating set temperature based on the current supply air set temperature to improve the current dry and hot air situation. Therefore, according to the glycol reheating set temperature, the set recovery pipe temperature TT29set is input to determine whether the monitored recovery pipe temperature TT29 of the glycol in the pipe is less than the set recovery pipe temperature TT29set. If so, enter the pre-cooling mode to adjust the temperature and flow of the glycol liquid. If the amount is too high, cooling and humidification are performed. At this time, the first bypass valve 10 and the second bypass valve 14 are closed, the heat supplement plate exchange valve 12 is opened, the heat recovery control valve 9 is opened, the two-way control valve 15 is opened, and the three-way control valve 16 is closed; if not, it means that no additional operation is required, and the air-conditioning system enters the standby mode for standby. At this time, the first bypass valve 10 and the second bypass valve 14 are closed, the heat supplement plate exchange valve 12 is closed, the heat recovery control valve 9 is closed, the two-way control valve 15 is closed, the three-way control valve 16 is closed, and the circulating water pump 11 is stopped, waiting for the actual environment temperature to change before switching to other working modes.

[0041] In this embodiment, after the air-conditioning system enters any mode, multiple temperature sensors and multiple temperature and humidity sensors will continue to obtain corresponding temperature and humidity related data. When it is found that the requirements for mode switching are met, they will automatically readjust and continue to switch the current mode accordingly, so that the air-conditioning system can be adjusted in real time and always work in the most appropriate state.

[0042] In an industrial production workshop, the air conditioning system adopts constant temperature and humidity control, the indoor temperature setting value TT24 is 20℃, the humidity setting value HT24 is 8g / kg, and the air conditioning box wind speed is controlled by the positive pressure in the workshop. When outdoor meteorological parameters such as outdoor temperature and humidity change, the operation mode of the exhaust heat recovery air conditioning system will also be adjusted accordingly.

[0043] At a certain moment in winter, such as noon, the outdoor temperature TT20 is 10℃ and the humidity HT20 is 5g / kg. The control system determines that the outdoor humidity HT20 is less than the humidity setting value HT24, the outdoor temperature TT20 is less than the temperature setting value TT24, the air temperature TT21 after the preheating coil is greater than 0℃, the preheating pipe temperature TT27 is greater than -2℃, and ethylene glycol has enough heat to heat the air to the set supply air temperature, that is, TT23>TT24, and the heat recovery air conditioning system enters the preheating and reheating mode.

[0044] The air conditioning system starts to work. The outdoor air in winter enters the air conditioning box 18 and is preheated by the preheating coil 1. It is cooled and dehumidified by the surface cooling coil 2. The fresh air temperature is heated to the required room temperature by the reheat recovery coil 3. The air is humidified by the humidifier 4 and sent to the room 6 by the air supply fan 5. The air exhausted from the room 6 recovers heat by the heat recovery coil 7 and is exhausted from the room by the exhaust fan 8. The ethylene glycol liquid is filled in the pipe 17. After the ethylene glycol liquid absorbs heat in the heat recovery coil 7, it is sent to the supplementary heat exchanger 13 by the circulating water pump 11 for heating. The heated ethylene glycol liquid is sent to the reheat recovery coil 3 to heat the fresh air. After the ethylene glycol liquid exchanges heat with the fresh air, it carries the residual heat into the preheating coil 1 to preheat the air. After the ethylene glycol liquid completes the air preheating, it returns to the heat recovery coil 7 to complete the initial cycle.

[0045] When it is afternoon, the outdoor temperature TT20 drops to 5℃, and the control system finds that the return air reheat energy TT23 is less than the set 20℃, which means that it is not enough to rely on the return air reheat energy to complete the indoor heating. Therefore, the air-conditioning system compares the data of the energy T27 in the reheat pipe and the energy TT29 in the recovery pipe, and finds that T27>TT29. Then the air-conditioning system enters the pre-cooling and reheating mode, closes the first bypass valve 10 and the second bypass valve 14, and opens the heat supplement plate valve 12, the two-way control valve 15 and the three-way control valve 16 to supplement heat, thereby stabilizing the indoor temperature at 20℃.

[0046] When the outdoor temperature continues to drop to 0℃ at night, the control system finds that the air temperature T21 passing through the preheater is less than 0℃, which means that some components may be frozen. Therefore, the air conditioning system enters the surface cooler antifreeze mode, closes the first bypass valve 10, the second bypass valve 14 and the heat supplement plate valve 12, and opens the heat recovery control valve 9, the two-way control valve 15 and the three-way control valve 16, thereby redistributing the energy of the reheater, reducing the possibility of component freezing, and continuing to operate stably.

[0047] In summary, the air-conditioning system can automatically adjust the working mode, which solves the problems of passive recovery and the need for manual intervention in the air-conditioning system in the prior art; in addition, the working mode of the air-conditioning system is subdivided into 9 types and adjusted accordingly. The adjustment process is smooth and the mode switching is accurate, which effectively solves the problem that the actual working mode is not energy-efficient enough and is significantly progressive.

[0048] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. An exhaust heat recovery air conditioning system with mode adjustment, characterized in that: The exhaust air heat recovery air conditioning system includes nine modes, namely: precooling and reheating mode, precooling and reheating bypass mode, precooling and reheating heat supplement mode, surface cooler anti-freezing mode, recovery coil anti-freezing mode, preheating and heat supplement mode, preheating and reheating mode, precooling mode and standby mode; The mode adjustment method is as follows: Input the set supply air temperature TT24, supply air humidity HT24 and flow rate into the exhaust air heat recovery air conditioning system; at the same time, input the outdoor air temperature TT20 and outdoor air humidity HT20 into the exhaust air heat recovery air conditioning system; record the return air reheating energy as TT23, the energy in the reheating pipeline as T27, the energy in the recovery pipeline as TT29, the air temperature passing through the preheater as T21, and the return water temperature of the ethylene glycol liquid in the preheater as TT27; When HT20>HT24, judge whether TT23>TT24 is satisfied. If it is satisfied, enter the precooling and reheating mode, close the first bypass valve (10), the second bypass valve (14) and the heat supplement plate heat exchanger valve (12), and open the heat recovery control valve (9), the two-way control valve (15) and the three-way control valve (16); if it is not satisfied, continue to judge whether T27<TT29 is met. If it is met, enter the precooling and reheating bypass mode, close the second bypass valve (14) and the heat supplement plate heat exchanger valve (12), and open the first bypass valve (10), the heat recovery control valve (9), the two-way control valve (15) and the three-way control valve (16); if it is not met, enter the precooling and reheating heat supplement mode, close the first bypass valve (10) and the second bypass valve (14), and open the heat supplement plate heat exchanger valve (12), the two-way control valve (15) and the three-way control valve (16); When HT20 ≤ HT24, it is judged whether it belongs to the case of TT20 ≤ TT24. If it belongs, it is further judged whether T21 is less than 0°C. If it is less, the reheater energy is redistributed, entering the anti-freezing mode of the surface cooler, closing the first bypass valve (10), the second bypass valve (14) and the supplementary heat exchanger valve (12), and opening the heat recovery control valve (9), the two-way control valve (15) and the three-way control valve (16); if it is not less, it is judged whether TT27 < -2°C is satisfied. If it is satisfied, it enters the anti-freezing mode of the recovery coil, closing the first bypass valve (10), the three-way control valve (16) and the supplementary heat exchanger valve (12), and opening the second bypass valve (14), the heat recovery control valve (9) and the two-way control valve (15). If it is not satisfied, it is judged whether the ethylene glycol liquid has enough heat to heat the air to the supply air temperature TT24. If it does, it enters the preheating and reheating mode. If not, it enters the preheating and supplementary heat mode, opening the supplementary heat plate, the supplementary heat exchanger valve (12), the heat recovery control valve (9), the two-way control valve (15) and the three-way control valve (16), and closing the first bypass valve (10) and the second bypass valve (14); if it does not belong, the ethylene glycol reheating set temperature TT29set is input, and it is judged whether TT29 < TT29set is satisfied. If it is satisfied, it enters the precooling mode, closing the first bypass valve (10), the second bypass valve (14), the supplementary heat exchanger valve (12) and the three-way control valve (16), and opening the heat recovery control valve (9) and the two-way control valve (15). If it is not satisfied, it enters the standby mode, closing the first bypass valve (10), the second bypass valve (14), the supplementary heat exchanger valve (12), the heat recovery control valve (9), the two-way control valve (15) and the three-way control valve (16), and the circulating water pump (11) stops running.

2. The exhaust heat recovery air conditioning system with mode adjustment according to claim 1, characterized in that: A plurality of temperature sensors are arranged on the air handling unit (18) and the pipeline (17) in the air conditioning system.

3. The exhaust heat recovery air conditioning system with mode adjustment according to claim 2, characterized in that: In the air conditioning system, a first temperature and humidity sensor (20) is arranged at the front end of the preheating coil (1), a first temperature sensor (21) is arranged at the front end of the surface cooling coil (2), a second temperature sensor (22) is arranged at the front end of the reheating recovery coil (3), a third temperature sensor (23) is arranged at the front end of the humidifier (4), a second temperature and humidity sensor (24) is arranged at the rear end of the supply air fan (5), a third temperature and humidity sensor (25) is arranged at the front end of the heat recovery coil (7), and a fourth temperature sensor (26) is arranged at the rear end of the heat recovery coil (7).

4. The exhaust heat recovery air conditioning system with mode adjustment according to claim 2, characterized in that: When HT20 > HT24 outdoors, the air conditioning system judges whether the return air reheating energy carried by the ethylene glycol liquid after heat recovery through the heat recovery coil (7) can heat the air to the supply air temperature TT24 according to the data transmitted by the seventh temperature sensor (29) at the rear end of the heat recovery control valve (9). If it can, the pre-cooling and reheating mode is started, the three-way control valve (16) is opened, the ethylene glycol liquid flows into the reheating recovery coil (3), and at the same time, the two-way control valve (15) is controlled to adjust the flow rate of the ethylene glycol liquid entering the reheating recovery coil (3) to control the air heating temperature.

5. The exhaust heat recovery air conditioning system with mode adjustment according to claim 1, characterized in that: In the case of HT20>HT24, dehumidification is performed through the surface cooling coil (2) in the air conditioning system to reduce the fresh air received by the air conditioning system to the dew point temperature.

6. The exhaust heat recovery air conditioning system with mode adjustment according to claim 1, characterized in that: The air conditioning system is arranged in a room (6), a group of preheating coils (1) are placed in front of the surface cooling coils (2) in the air-conditioning system, a group of heat recovery coils (7) are placed in front of the exhaust fan (8), the inlet of the reheat recovery coil (3) is connected to the outlet of the heat recovery coil (7), the outlet of the reheat recovery coil (3) is connected to the inlet of the preheating coil (1), and the outlet of the preheating coil (1) is connected to the inlet of the heat recovery coil (7), thereby completing the cycle; A circulating water pump (11) is installed on the pipeline between the heat recovery coil (7) and the reheat recovery coil (3), and a supplementary heat plate exchanger (13) is installed behind the circulating water pump (11); A two-way control valve (15) is installed before the inlet of the reheat recovery coil (3), a heat recovery control valve (9) is installed after the outlet of the heat recovery coil (7), a three-way control valve (16) is installed at the outlet of the reheat recovery coil (3), a second bypass valve (14) is installed before the circulating water pump (11), and a first bypass valve (10) is installed after the supplementary heat exchanger (13).

7. The exhaust heat recovery air conditioning system with mode adjustment according to claim 6, characterized in that: The first bypass valve (10), the circulating water pump (11), the heat supplement plate exchanger (13), the heat supplement plate exchanger valve (12) and the second bypass valve (14) constitute a hydraulic control unit. The hydraulic control unit receives signals from a plurality of temperature sensors arranged on the air conditioning box (18) and the pipeline (17) of the air conditioning system, and controls the opening and closing of the valve according to the signals from the plurality of temperature sensors.

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