Hottest solar water heater refrigerator compound m

2022-08-04
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Solar energy, thermal actuator is designed to confirm many parameters of the actuator, such as clearance, friction, leakage, etc. according to the overall performance requirements of the system. Water heater, refrigerator, hybrid machine, experiment

[Abstract] a series of experiments have been carried out on a new type of solar water heater refrigerator hybrid machine experimental device that can provide both hot water and refrigeration, By changing the working conditions of the device, the performance experiments are carried out under different working conditions, and the optimal working conditions of the device are obtained, which lays a foundation for further research in the future

research background

with the rapid increase of the earth's population, the acceleration of resource consumption and the intensification of the energy crisis, the fate of mankind is facing increasingly severe challenges. Using the inexhaustible and abundant solar energy is an important means to solve the energy crisis at home and abroad. Has been increasingly valued and developed. China is a country with abundant solar energy resources, which are wasted in vain. Taking Hebei, Shanxi and other places as examples, the annual total amount of solar radiation in this area is 586 ~ 670 kJ/cm2, which is equivalent to burning 200 ~ 230 kg of standard coal. It can be seen that the effective use of solar energy is of great significance to our populous country. Among them, the solar water heater is a typical solar thermal utilization, and China has a unique school in the development of solar water heater. According to statistics, in 1992, the total sales volume of solar energy sealed experimental water heaters used in food, pharmaceutical, daily chemical and other industries for flexible packaging film was 950000 m2, while that in China was 500000 m2, more than half of the world total. The data further shows that the number of solar water heaters in China will grow from 4.3 million m2 in 1995 to 12.53 million m2 in 2000, with an average annual production and sales volume of 2.5 million m2. If each household uses 2 M2 solar collectors, at least 5million users in China will use solar collectors as the main channel for domestic hot water by 2000. In addition, with the development of society and the improvement of people's living standards, air conditioners and refrigerators are widely used. At present, freon is widely used in air conditioners and refrigerators. However, the destruction of the ozone layer by freon poses a challenge to human survival. Therefore, the use of solar energy for refrigeration to achieve the goal of green and environmental protection is the direction of many researchers in the world. It is a brand-new idea to effectively combine solar water heater and solar refrigeration to achieve the comprehensive utilization of solar energy resources. While providing hot water, cooling at the same time is a new idea. Now we have made it a reality in the laboratory [1 ~ 3]

1 solar water heater refrigerator compound machine experimental device

the construction idea of the device is as follows: the adsorption bed for adsorption refrigeration is directly installed into the hot water tank of the solar water heater, so that the solar heat collected by the collector of the solar water heater system during the day can heat both the water in the hot water tank and the adsorption bed. Heating the adsorption bed will cause the adsorbent in the adsorption bed to desorb the refrigerant; In the evening, the hot water in the hot water tank is used up or put into another insulated water tank for users' use. At the same time, the cold water is put into the water tank equipped with the adsorption bed. Because the adsorption bed is directly cooled by the cold water, the temperature will soon drop to the required temperature. At this time, the adsorbent in the adsorption bed is allowed to absorb the refrigerant desorbed during the day to produce refrigeration effect. The cooling capacity obtained by the system can be provided to users through the cold storage device when necessary. Figure 1 is a system diagram of the device

Fig. 1 experimental device of solar water heater refrigerator

1. hot water tank; 2. hot water; 3. adsorption bed; 4, 7, 10. valves; 5. condenser

6. liquid storage tank; 8. insulation box; 9. evaporator; 11. experimental results and analysis of vacuum tube collector

2 water heater refrigerator compound machine

in order to have a comprehensive understanding of the performance of the device and find out the optimal working condition of the device, first use electric heating to simulate solar energy. For the solar collector, the average solar radiation energy received by the collector is usually 500 W/m2, so the 1500 W electric heater is selected to simulate the energy collected by the 3 M2 collector. A temperature controller is installed on the circuit of the electric heater. In order to change the maximum desorption temperature of the adsorption bed, observe the change of the refrigeration cop of the device with the maximum desorption temperature. The water temperature is respectively controlled at 92 ℃, 81 ℃, 72 ℃, and the adsorption bed temperature is correspondingly controlled at 85 ℃, 73 ℃, 66 ℃. The experimental data obtained are shown in Table 1 to table 3. Table 1 data record of the original parameters of Experiment 1

Table 2 data record of the original parameters of Experiment 2

Table 3 data record of the original parameters of Experiment 3 h. 120 kg of hot water at 92 ℃ and 9kg of ice at - 1.5 ℃ were obtained. The relevant original parameters during the cyclic operation of the system are shown in Table 1

in Experiment 2, the water temperature was controlled at 81 ℃, the average temperature of the adsorption bed was 73 ℃, 6 kg of water was put into the refrigerator and 120 kg of water was put into the hot water tank. The system operated for 22.8 hours and consumed 12.36 kw h. 120 kg of hot water at 81 ℃ is obtained, and the temperature in the refrigerator is -1.2 ℃. The relevant original parameters during the cyclic operation of the system are shown in Table 2

in Experiment 3, the water temperature was controlled at 72 ℃, the average temperature of the adsorption bed was 66 ℃, 4.5 kg of water was put into the refrigerator and 120 kg of water was put into the hot water tank. The system operated for 19.5h and consumed 10.95 kw h. 120 kg of 72 ℃ hot water is obtained, and the temperature in the refrigerator is -1.2 ℃. The relevant original parameters during the cyclic operation of the system are shown in Table 3

process the original data, draw and calculate. The calculation results are shown in Table 4. Figures 2 to 10 show the time-varying curves of water temperature in the hot water tank and adsorption bed temperature, the time-varying curves of refrigerant and water temperature in the ice box in the evaporator and the thermodynamic cycle diagram of the device under three different working conditions. The following formula is used for calculation:

copsystem = external cooling capacity of the system/total heating capacity provided by the outside world to the system (1)

copcycle = external cooling capacity of the system/heating capacity of the adsorption bed (2)

η= Hot water heat generated by the system to the outside world/total heating capacity provided to the system by the outside world (3)

cop60 = cooling capacity generated by the system to the outside world/(total heating capacity provided to the system by the outside world - heat from 60 kg water - heat leakage) (4) table 4 experimental performance results of the compound machine device

due to the defects of the experimental device, there is a large heat leakage, which reduces the cop of the system, and the hot water tank of the device is relatively large, For example, 120 kg of water is not required for the commercialization of the complex machine, and only 60 kg is required for household use. Therefore, a 60 kg hot water system is simulated here, and its corresponding cop is defined as cop60. When calculating cop60, the denominator is the total heating amount provided to the system from the outside minus the heat obtained by 60 kg of water and then minus the heat leakage. The formula is as follows (4). Therefore, the heat leakage test of the device at 92 ℃, 81 ℃ and 72 ℃ was specially conducted, and the heat leakage power was calculated. The heat leakage per hour was 0.61, 0.31 and 0.2 kW respectively h。

in the following figures, figure 2 to figure 4 are the variation diagram of system parameters with time under 92 ℃ working condition and the thermodynamic cycle diagram of the device, figure 5 to figure 7 are under 81 ℃ working condition, and figure 8 to figure 10 are under 72 ℃

Fig. 2 time varying curve of water temperature in water tank and adsorption bed temperature in Experiment 1

1. water temperature in water tank; 2. adsorption bed temperature

Fig. 3 time varying curve of refrigerant in evaporator and water temperature in ice box in Experiment 1

1. refrigerant temperature in evaporator; 2. water temperature in the ice box

Fig. 4 thermodynamic cycle diagram of Experiment 1

Fig. 5 time varying curve between water temperature in the water tank and the temperature of the adsorption bed in Experiment 2

1. water temperature in the water tank; 2. adsorption bed temperature

Fig. 6 time varying curve of refrigerant in evaporator and water temperature in ice box in Experiment 2

1. refrigerant temperature in evaporator; 2. water temperature in the ice box

Fig. 7 thermal cycle diagram of Experiment 2

Fig. 8 time varying curve of water temperature in the water tank and adsorption bed temperature in Experiment 3

1. water temperature in the water tank; 2. adsorption bed temperature

Fig. 9 time varying curve of refrigerant in evaporator and water temperature in ice box in Experiment 3

1. refrigerant temperature in evaporator; 2. water temperature in the ice box

Figure 10 thermodynamic cycle diagram of Experiment 3

the following description can be made from the figure: it can be seen from figures 2, 5 and 8 that when the water in the water tank is heated by the electric heater, the initial temperature begins to rise, and with the heating, the water temperature rises to the controlled temperature and remains constant. After heating, transfer the hot water in the water tank to another water tank and inject cold water. At this time, the water temperature in the water tank drops to the injected cold water temperature. After the adsorption bed starts to adsorb refrigerant, due to the existence of adsorption heat, the water temperature in the water tank rises slightly during the adsorption process, and a cycle process is basically completed after about 20 hours. It can also be seen that there is a lag between the temperature of the adsorption bed and the water temperature (about 8 ℃) during the heating process, which is mainly caused by the surface contact thermal resistance of the metal shell of the adsorption bed and the thermal resistance between the activated carbon. After heating, cold water is put into the water tank, and the temperature of the adsorption bed is reduced to almost the same as that of the injected cold water in a short time, so that the pressure in the adsorption bed is reduced to the evaporation pressure, so as to generate the evaporation refrigeration process of the refrigerant. As the cold water in the water tank is a strong cold source, the temperature of the adsorption bed will not rise very high during the adsorption process, and the adsorption refrigeration effect is excellent. Figures 3, 6 and 9 show that during the heating desorption process, the temperature of the refrigerant in the evaporator is basically unchanged, while during the adsorption process, the refrigerant liquid in the evaporator quickly drops to the evaporation temperature, transferring the cooling capacity to the water supply and freezing the water. It can also be seen that the temperature drop of water in the refrigerator is basically synchronized with the temperature drop of refrigerant in the evaporator, which fully shows that the design of the evaporator is very reasonable and can effectively convert the phase change latent heat of refrigerant into the cooling capacity of water. After the water in the ice box drops to the freezing point, because ice needs to take away a large amount of latent heat, the temperature of the water in the ice box will remain unchanged for a long time at the phase change temperature point, and supercooling will occur at the end of ice formation, further reducing the temperature. Figures 4, 7 and 10 show the relationship between the pressure and temperature of the adsorption bed during a cycle of the recombiner system, which is different from the constant pressure heating desorption in the ideal cycle

figures 11, 12 and 13 show the change of refrigeration cop of the device with desorption temperature. It can be seen that under fixed working conditions, namely, the adsorption temperature is 22 ℃, 23 ℃, the external ambient temperature is 15 ℃ (the ambient temperature is related to the condensation temperature), and the evaporation temperature is about -2.5 ℃. Within the desorption temperature range of 60 ℃ to 90 ℃, the cop of the device increases with the increase of the maximum desorption temperature. Since the solar water heater refrigerator complex uses water as the heating medium, the boiling point of water under normal pressure is 100 ℃, and there is a heat transfer temperature difference between water and the adsorption bed, the maximum temperature of the adsorption bed will be about 92 ℃, so this set of experimental data can effectively show the performance of the device. This reminds us that in the future, when using the vacuum tube collector directly irradiated by solar energy as the heating source, we should heat the water as much as possible to make the water temperature reach more than 90 ℃, which can be achieved through reasonable design. In the experiment, it is found that under the high temperature condition, the device solution

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