مرضیه طبیبی

Cooling systems such as refrigeration and air conditioning are considered as basics of everyday life. In these years, the demand for both energy/associated services to address economic and social along with ameliorate human comfort and health is continuously increasing. Since approximately 1850, the global use of fossil fuels (coal, oil and gas) has dramatically raised to dominate energy supply. However, the required energy for the above-mentioned applications is mainly generated by non-renewable electricity. Due to the depletion of fossil fuels as a source of electricity, the development of renewable energies for such systems is necessary. Considering all these issues, as cooling needs, most of the time coincides with the solar radiation availability; therefore, exploring solar energy seems an exciting idea. A number of investigations were performed to design/develop new cooling techniques using solar energy. A solar cooling system is capable of considerably reducing the environmental effects of traditional refrigerating machines while allowing significant energy saving. The present work searches for the best choice of configuration/design factors of food refrigeration systems combined with solar-powered absorption chillers unit in Ahvaz city as a case study.

 In the present study, a linear parabolic collector with specific dimensions, was made, so that first, the initial design of the collector with longitudinal dimensions of 1 and a width of 0.6 meters was selected by Katia software, and then using related relations and calculations of other structural parameters based on which the collector was built, the collector simulation was performed using NASA radiation data for the place and time of the experiments and by using the Transient Simulation Software and its performance in the days of the month July, August and September 2019 were reviewed and evaluated. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2. Also, the necessary calculations were performed on the results of performance tests by Excel software, and diagrams of changes in the radiant energy absorbed by the collector and the efficiency of the radiated energy absorbed were drawn from 10:00 AM to 6:00 PM. Using the diagrams obtained from the system simulation in TRNSYS (Transient System Simulation Tool) software, it is concluded that the built-in collector has the ability to produce a fluid with a temperature above 98 degrees Celsius required for the absorption chiller in July, August, and September.

 According to the evaluations of the collector's performance in the three months of July, August, and September from 10 AM to 6 PM showed that collector energy and efficiency reached their maximum values in July with 318.240 w-h/m2 and 63.05 %, respectively. While in August, the amount of energy and efficiency was found to be 299.311 w-h/m2 and 61.94%, respectively. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.The minimum value of the parameters were recorded as 283.379 w-h/m2 and 61% in September, respectively. The potential analysis conducted showed an excellent saving potential in terms of energy obtained. According to the results, the useful collector energy was achieved to be 227.664 w-h/m2, 217.006 w-h/m2, and 210.406 w-h/m2 in July, August, and September, respectively. According to the obtained results, the maximum refrigeration load needed for the studied cold storage was about 126324 w. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.

 The development of renewable energies for such systems is necessary. Solar cooling system for food products cold storage in Ahvaz city is a promising and innovative alternative to decline the peak energy consumption generated by the combustion of fossil fuels, especially during the summer months.