| In recent years, since the awareness of environment, energy crisis peple have paid more attentions to solar energy which is clean and renewable. However, solar energy is not stable due to the presence of intermittent supply of solar energy which is caused by the influence of the weather. Therefore, the storage tank is normally set to regulate the heat supply in order to maximize the use of solar energy in solar energy systems. For solar air-conditioning system, refrigeration equipment continuously can provide cooling to room through two energy storage methods, such as heat storage and cooling storage. This paper studies energy storage impact on the performances of solar ejector-compression refrigeration system and device optimization. It gives the best tank volume, which makes sense for the design of solar ejector refrigeration system. The main contents are as follows.1. This paper analyzed the operating principle of ejector refrigeration system and describes in detail the model of main equipment such as ejectors, heat exchangers, flat-plate collector, stratified storage tank. Then the mathematical model of the main components used in TRNSYS was presented such as flow diverter, flow mixer, plate collector, differential controller,(time, temperature flow) controller and calculator.2. Three ejectors were designed which evaporation temperature were independently 5, 15 and 25 ℃. The performance calculation of three ejectors was analysised.3. Distribution of building cooling load and variation of dry bulb temperature, wet bulb temperature were obtained through analyzing the energy consumption of buildings with TRNSYS.4. Collector simulated system of solar ejector refrigeration was established by TRNSYS. The variation of generation temperature, cooling capacity and COP were simulated under different S(ratio of tank volume and collector area) when design evaporation temperature was 5 ℃, 15 ℃or 25 ℃ respectively. Result shows that the optimum S for the system varies from 0.015 to 0.03 when R141 b is chosen as the working fluid and evaporation temperature ranges from 5 to 15℃ in Taiyuan. The higher design evaporation temperature is, the greater the value of S is.5. Ejector refrigeration system with heat and cold storage was researched. Collector system was simulated when the capacity increase of collector system equipment is 10%, 20% and 30% respectively. It is founded that when the total collector area and volume of heat storage tank in the thermal simulated system is 94 m2 and 1.41 m3, the operation time of ejector refrigeration system is 66.7% of the required time length and the total cooling is 99% of the cooling demand. Store excess cooling to provide to the time period when refrigeration system can not run. When the volume of cooling storage tank is 1.1 m3, refrigeration system can basically meet the cooling load demand throughout the day(8:00- 18:00).6. Ejector refrigeration system with only heat storage was researched. A new thermal simulated system contained two sets of collector device was established by TRNSYS. Two control schemes were implemented and for each group device capacity of thermal simulated system is determined by the hourly variation of solar radiation and heat load of generator during the period of the supply of heat. System operation was simulated from July 31 to August 2 including the length of cooling time, temperature of water in heat storage tank and generator, collector efficiency, cooling capacity and COP. Studies show that when the total collector area is 120m2 and total volume of heat storage tank is 5.5m3, the refrigeration system can basically meet the cooling load demand of room throughout the day(8:00- 18:00). And the system runs better when a day is divided into four time periods. The operation time of ejector refrigeration system is 90.8% of the required time length and the total cooling can deliver up to 140% of the cooling demand. However, there is no cold storage system, ejector refrigeration system with only heat storage cooling caused a large number of cooling loss. |
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