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Pineapple (Ananascomosus) slices were dried with the aid of a heat pump assisted dryer (HPD). During this process, air velocity was kept constant at 1m/s, while air temperatures were changed as 37°C, 40°C and 43°C. The drying air was also circulated by using an axial fan in a closed cycle and fresh air was not allowed into the system. The drying rate and drying time were significantly influenced by drying temperature. It was observed that drying temperatures had significant effects on the drying rate and drying time. During the conduct of the study, pineapple slices were dried at 37, 40 and 43°C for 465, 360 and 290 min, respectively. The specific moisture extraction ratio (SMER) values were observed to change as drying temperatures were changed. The drying rate curves indicated that the whole drying process occurred in the falling rate period. Seven well-known thin-layer models (Lewis, Henderson &Pabis, Logarithmic, Page, Midilli & Kucuk, Weibull and Aghbashlo et al.) were employed to make a prediction about drying kinetics through nonlinear regression analysis. The Midilli & Kucuk and Aghbashlo et al. models were consistent with the experimental data. Fick’s second law of diffusion was used to determine the moisture diffusivity coefficient ranging from 3.78×10–9 to 6.57×10-9  m2/s the each of the above mentioned temperatures. The dependence of effective diffusivity coefficient on temperature was defined by means a fan Arrhenius type equation. The activation energy of moisture diffusion was found to be 75.24kJ/mol. Article History: Received: July 18th 2017; Received: October 27th 2017; Accepted: January 16th 2018; Available onlineHow to Cite This Article: Tunçkal, C., Coşkun, S., Doymaz, I. and Ergun, E. (2018) Determination of Sliced Pineapple Drying Characteristics in A Closed Loop Heat Pump Assisted Drying System. International Journal of Renewable Energy Development, 7(1), 35-41.https://doi.org/10.14710/ijred.7.1.35-41

Traditional solar hot water system (SDHW) is an important system for the use of renewable energy sources. In this system, while water is heated by sun in summer or hot days, it is heated by electric heaters in winter, or cold days. So efficiency of this system is low in winter because of very high electric consumption. This problem can be solved using heat pump instead of electric heaters. In this study, a heat pump assisted solar domestic hot water system (HP_SDHW) was designed to increase efficiency. Both systems were modelled and simulated depending on time using (TRNSYS) program. An analysis was performed through the year for both systems at SARAJEVO/ Bosnia and Herzegovina conditions. As a result of the annual analysis, it was found that the HP_SDHW system consumes approximately 40% less electricity than the traditional SDHW system. The solar fraction of the HP_SDHW (%67) was found higher than the SDHW system (%46).

In this study, to evaluate the comparative experimental performances, a frigorific air conditioning system using HFO1234yf and R134a was developed and refrigerated air was introduced into a conditioned room. The experiment was carried out at different condenser inlet temperatures and using the refrigerants at different charges, 1250, 1500, and 1750 grams. Experiments were conducted for a standard frigorific air conditioning system using the HFO1234yf and R-134a system. Air flow was introduced to the conditioned room for 60 minutes for each performance test. The results revealed that the temperature gradient in time was comparable for both refrigerants. The results of this investigation propose utilising HFO1234yf as a replacement for the currently favoured R134a in a frigorific air conditioning system