Exergetic performance assessment of a ground-source heat pump drying system

Abstract

SUMMARYIn evaluating the efficiency of heat pump (HP) systems, the most commonly used measure is the energy (or first law) efficiency, which is modified to a coefficient of performance (COP) for HP systems. However, for indicating the possibilities for thermodynamic improvement, energy analysis is inadequate and exergy analysis is needed. This study presents an exergetic assessment of a ground-source (or geothermal) HP (GSHP) drying system. This system was designed, constructed and tested in the Solar Energy Institute of Ege University, Izmir, Turkey. The exergy destructions in each of the components of the overall system are determined for average values of experimentally measured parameters. Exergy efficiencies of the system components are determined to assess their performances and to elucidate potentials for improvement. COP values for the GSHP unit and overall GSHP drying system are found to range between 1.63-2.88 and 1.45-2.65, respectively, while corresponding exergy efficiency values on a product/fuel basis are found to be 21.1 and 15.5% at a dead state temperature of 278C; respectively. Specific moisture extraction rate (SMER) on the system basis is obtained to be 0:122 kg kW À1 h À1 : For drying systems, the so-called specific moisture exergetic rate (SMExR), which is defined as the ratio of the moisture removed in kg to the exergy input in kW h, is also proposed by the authors. The SMExR of the whole GSHP drying system is found to be 5:11 kg kW À1 h À1 :

A Comparative Study on Exergetic Performance Assessment for Drying of Broccoli Florets in Three Different Drying Systems

“…[13][14][15][16][17] In these previous studies, the drying process was thermodynamically modeled by Dincer and Sahin, [14] and drying of different products such as wheat kernel, [18] pistachio, [13] red pepper slices, [15] potato, [16,19] apple slices, [20] pumpkin, [17] laurel leaves, [21,22] pasta, [23] green olive, [24] and mint, [25] was evaluated in terms of energetic and exergetic aspects using various drying devices, such as fluidized bed dryers, solar drying cabinets, cyclone-type dryers, convective-type hot air dryers, and heat pump dryers. In addition, other exergetic studies on drying also included a solar greenhouse, [26] a freeze-drying process, [27] a detailed review, [28] and mathematical modeling.…”

Exergy Analysis of a Ground-Coupled Heat Pump Heating System with Different Terminals

“…Exergy analysis has been applied to GCHP systems by some researchers [10][11][12][13][14]. Hepbasli and Akdemir [10] presented an energy and exergy analysis of a GCHP system with a fan coil unit (FCU) as terminal.…”

“…The results show that the energetic and exergetic efficiencies of the system increase when increasing the buried depth of horizontal GHE. Kuzgunkaya and Hepbasli [13] presented an exergetic assessment of a GCHP drying system in Turkey. The exergy destructions in the overall GCHP system are quantified using the average values of experimentally measured parameters.…”

Exergoeconomic Analysis of Plum Drying in a Heat Pump Conveyor Dryer

“…[4] By using an exergy analysis method, magnitudes and locations of exergy destructions (irreversibilities) in the whole system can be identified, and potential for energy efficiency improvements can be introduced. [5] Mathematical models for exergy analysis of drying of biological products have been developed by some investigators. [4,[6][7][8][9] The energy analysis method has been widely used for evaluating the performance of food systems (especially food dryers), though studies on exergy analysis are relatively few in numbers.…”