Exergetic Evaluation of Heat Exchanger with Multiple Inserts for Greenhouse Heating

The heat exchanger performance is vital for attaining higher overall performance of the greenhouse heating system. The exergetic performance is evaluated for the heat exchanger using twisted tape inserts for greenhouse heating. Single, a set of two, and four twisted tapes of TR 2.5-3.5 are considered for the analysis by varying Reynolds number (Re) from 3000 to 15000. A set of two twisted tapes causes a decrease in total entropy generation up to Re of 7650 and increases beyond this value. The maximum and minimum values of the Bejan number are obtained for the smooth tube and the tube with twisted tapes (four) in “counter-swirl” orientation, respectively. The twisted tapes are feasible under the Reynolds number of 9042 based on the analysis of the entropy generation number. The minimum value of total entropy generation is obtained as 0.00035 for the four twisted tapes in counter-swirl orientation (FTT-COUS). The maximum exergy efficiency is observed for a twisted tape insert at a pitch ratio of 3.5.