Heat transfer performance investigation on a finned tube adsorbent bed with a compound parabolic concentrator (CPC) for solar adsorption refrigeration

Abstract

In this work, activated carbon-methanol was used as the working pair in a solar adsorption refrigeration system (SAR). The thermal conductivity of the activated carbon was very poor, resulting in performance delays of the system. To improve the performance of the heat transfer for the adsorbent bed, a new adsorbent bed with finned tubes was designed and studied using commercial computational fluid dynamics (CFD) software. Two-dimensional (2D) numerical models of two kinds of adsorbent tubes (finned and smooth tubes) were constructed and simulated. The two different 2D numerical models had similar cell numbers and the same boundaries and initial conditions. An experiment for a grid verification model of the designed finned tube was conducted, and the model of the finned tube was validated via comparison between the numerical and experimental results. In addition, the heat performances of the newly designed finned tube and the smooth tube were compared in this paper. The temperature gradients of the activated carbon in the smooth and finned tubes were approximately 28.1 °C and 4 °C during isosteric heating, respectively. The conclusions are that the fins had a large effect on the thermal performance of SAR, and the possibility that the methanol was adsorbed again by the activated carbon of the lower temperature part in the finned tubes during isobaric heating was decreased greatly. Moreover, the radial heat loss of the finned tube wall was also less than the smooth tube, which may be an important factor for improving the performance of the system effectively.