Mathematical and Experimental Analysis of an Internally Finned Double Pipe Heat Exchanger for Coupling of Solid Oxide Fuel Cell Cathode Exhaust Heat and Vapor Absorption Refrigeration System on Refrigerated Trucks

Abstract

Solid oxide fuel cells (SOFC) generate electricity with high quality waste heat which if harnessed and used as energy source for vapour absorption refrigeration systems (VARS) will address the emission issues related to refrigerated transport infrastructure. The temperature range of the heat source required at the desorber of the VARS is between 120 and 200oC, while SOFCs cathode exhaust heat temperatures are 600oC and above. Therefore, an internally finned double pipe heat exchanger (DPHX) was development mathematically in this study with thermal oil as the coupling fluid and validated experimentally for indirect couplingof the SOFC cathode exhaust heat with the VARS.The experimental setup mimics a 5 kWe SOFC stack. Results showed that 1.84 kW of heat was recovered at a cathode exhaust flow rate of 24.64 L s-1 resulting in a heat exchanger effectiveness of 12.22 % and overall heat transfer coefficient of 60.15 W m-2 K-1. The recovered 1.84 kW of heat are able to power a single effect VARS on board a small refrigerated truck to supply 1 kW of cooling load. Results also revealed an exchanger effectiveness and overall heat transfer coefficient increase by 70.2 and 19.4 %, respectively, at a reduced exhaust flow rate of 7.347 L s-1. Further improvement of 81.1 and 39.22 %, respectively, of exchanger effectiveness and overall heat transfer coefficient was achieved at 4.653 L s-1exhaust flow rate.

A Comprehensive Review of Thermal Management in Solid Oxide Fuel Cells: Focus on Burners, Heat Exchangers, and Strategies

“…Tiwari et al [77] designed an innovative manifold microchannel heat exchanger with commercially available finned tubes as the geometric shape for microchannels and flow distribution through 3D-printed polymer manifolds, reducing manufacturing costs and enhancing performance, suitable for large-scale manufacturing (Figure 5b). Amakiri et al [78] conducted a mathematical model to describe a dual-pipe heat exchanger with internal fins to recover heat from SOFC cathode waste gases, investigating the capture and utilization of SOFC waste gases to provide energy for refrigerated trucks. Meier et al [79] presented a simple method to predict the thermal characteristics of a micro-SOFC system.…”