مطالعه تجربی در تجزیه و تحلیل عملکرد دینامیکی یک صفحه تخت خورشیدی تبرید جامد جذب برای یخ ساز

A flat-plate solid-adsorption refrigeration ice maker has been built for demonstration purposes. The working pair consists of methanol used as the refrigerant and activated carbon as the adsorption medium. The adsorbent bed is constructed of two flat-plate collectors, with a total surface area of 1.5 m2. Solar radiation can be simulated with quartz lamps and some important parameters such as temperature and pressure of each subsystem can be handled by a computer. The experimental results show that this machine can produce 4–5 kg of ice after receiving 14–16 MJ of radiation energy with a surface area of 0.75 m2, while producing 7–10 kg of ice after receiving 28–30 MJ of radiation energy with 1.5 m2. These are the most advanced results for a solar ice maker so far. All these successful achievements will speed up the commercial processing of a solar ice maker.

The application of solar energy instead of electricity to refrigeration appears logical for countries with a good supply of solar energy. In west China, there are many remote areas where electricity is absent, but the solar irradiation is plentiful, thus the utilization of solar energy to produce cold in these areas is very important. A solar-powered solid-adsorption refrigeration machine uses solar energy as the power, and has the added advantage that there are no moving parts in its running process, it is extremely easy to handle, and working pairs can easily be found, etc. Many researchers have demonstrated their research results on these machines, including Iloeje [1], Pons and Guilleminot [2], and Erhard et al. [3]. However, in recent years, the number of reports on solid-adsorption refrigeration has decreased. One of the main reasons is that the properties of the adsorption refrigeration machine are variable. It is interesting to further analyze the properties of solar refrigeration so as to speed up the application of the solar-adsorption refrigerator in commerce. In recent years, more attention has been paid to the utilization of solar energy in our research group. A new method of using solar energy to provide both heating and cooling by a hybrid system has been proposed by Wang et al. [4], and an experimental device in which an electric heater is used to simulate solar radiation was fabricated, with very successful experimental results. Meanwhile, a flat-plate solid-adsorption ice maker driven by solar energy was designed too. For this flat-plate device, the adsorbent bed was constructed of two flat-plate collectors, each with an area of 0.75 m2. This device also contains other subsystems such as a condenser, an evaporator, reservoirs, an ice box and connecting pipes. Solar radiation can be simulated with quartz lamps, and many parameters such as the temperature of the adsorbent and the temperature of the refrigerant can be obtained from measurement by means of thermocouples placed in different points of the system, and the desorbed refrigerant mass can be calculated in the reservoirs. From the simulated experiment results, it is possible to analyse the dynamic performance of the solar cooling system. In this the way, optimization of the solar refrigeration system design becomes possible.

A flat-plate solar-powered ice maker was fabricated for demonstrating and analysing the properties of solar solid-adsorption refrigeration. After several successful experiments had been carried out, many useful practical results can be suggested in this new design of a solar refrigerator. These include: (1) enhancing the heat transfer in the adsorbent, adopting heat transfer fins and decreasing the radial distance of the adsorbent from top to bottom; (2) every subsystem such as the adsorbent bed, condenser, and evaporator must be designed with the method of optimization, so that the efficiency of the solar refrigerator can be improved effectively; (3) the advanced technology of solid-adsorption refrigeration should be matched with solar water heater technology, so as to speed up the commercial application of solar solid-adsorption refrigeration. Based on these foundational works, a new advanced solar refrigerator has been developed in our laboratory, and excellent results have been obtained. With the research continuing, we believe that the applications of solar solid adsorption will be increasing rapidly.