A re-circulating heat pump dryer (HPD) system was designed, constructed and tested at steady-state and transient conditions. Refrigerant 134a was used as a refrigerant in this system. The tests were performed to observe behavior of HPD system. So, changes of temperature and relative humidity of drying air through the dryer and heat pump operating temperatures were observed during the drying process and effects of bypass air ratio (BAR) on the system's parameters as system performance and specific moisture extracted ratio (SMER) at steady-state were investigated. The HPD system was also tested to investigate temperatures and relative humidity changes of drying air during drying process on the system's parameters depend on time. Air flow rate circulated through the HPD system was 554 m 3 /h during the all tests. According to test results, the system's parameters did not change up to 40% of BAR. Then the coefficient at performance (COP) and SMER values were decreased after 40% of BAR. While SMER values changed between 1.2 and 1.4, COP sys changed between 2.8 and 3.3 depend on BAR. As well as during the drying process, the COP and SMER values were also affected and decreased depend on time.

This study examines experimentally the cooling application of a solar absorption system with interior energy storage that uses two different auxiliary systems. The experiments were performed at Uludag University, Bursa, Turkey on the 3rd and 4th of August 2010 that had the approximately same average outdoor temperature, 31°C. A solar hot water was delivered via a 40 m2 array of flat plate solar collectors that drove a lithium chloride (LiCl) absorption heat pump with a cooling power peak of 20 kW. A solar-powered air conditioning system was designed for heating and cooling in a test room that had a total floor space of 30 m2. Chilled water produced in the evaporator was supplied to the fan coil units, and the heat of condensation and absorption was rejected by means of a wet cooling tower. An electric heater and an air source heat pump were used as auxiliary systems for the absorption cooling application for two different cases when the solar energy was insufficient. Temperature variations were recorded for the absorption machine components, the test room, and the outdoors. The cooling energy, thermal energy, and daily average coefficient of performance (COP) of the absorption system were calculated for two days. Solar absorption cooling was considered for two different auxiliary systems and is presented in this manuscript. The results showed that the daily average COP of the absorption system was 0.283 for Case 1 and 0.282 for Case 2. For both cases, the interior energy storage of the absorption system enabled it to satisfy the cooling demand during the night while solar energy was not available.

In pandemic periods such as COVID-19, economic and sociological problems threaten human life and public order on a global scale. In these periods, the use of solar powered heating-cooling systems to meet the thermal needs of the hospitals and to provide the thermal comfort conditions offer important solutions for the elimination of technical, economic and environmental problems related to energy supply. In this study, covering the heating, cooling and hot water supply of a sample hospital building for the three largest cities of Turkey with a novel solar powered Li-Cl absorption heat pump system was investigated using the TRNSYS simulation program. The use of a unique NH3-H2O resorption system as a solar powered auxiliary system was also investigated. It was determined that the total annual hot water and cooling needs of the hospital buildings in all three provinces are supplied almost completely with the solar energy powered system without compromising the hygiene and thermal comfort of the occupants and the average annual solar fraction of total heating demands are calculated as 50%, 54% and 65% for İstanbul, Ankara and İzmir, respectively. In addition, depending on the use of solar energy, it has been observed that annually 126 tons of CO2 emissions were saved and an economic saving of 524 375 TL was achieved in total. Considering the problems about the energy supply during the epidemic periods, it was concluded that meeting the energy requirements of hospitals with clean, renewable and independent energy source will provide significant benefits to the countries.