Integrated Heat Regenerator (IHR) Designs with Hydrogen Preheater and Thermoelectric Generator for Power Enhancement of a 2 kW Fuel Cell Vehicle

Abstract

The power train efficiency of fuel cell vehicles (FCV) can be enhanced by improving the hydrogen energy utilization. Based on a mini FCV running on a 2 kW open-cathode Polymer Electrolyte Membrane (PEM) fuel cell, a waste heat recovery system design needs to be developed as an approach towards higher energy efficiency. The novelty of the system is on the integration of thermoelectric generator technology with hydrogen preheating process for a combined heat and power output. This manuscript presents the proposed integrated heat regenerator (IHR) designs, analysed using numerical computational modelling. Three IHR designs were proposed where the main design criteria are (i) a minimum of 10oC hydrogen preheating degree, and (ii) non-parasitic active cooling for the Thermoelectric generator (TEG) cells. Three design concepts were studied to identify its design and performance limitations. The numerical results were validated with theoretical modelling analysis for hydrogen exit temperatures and TEG surface temperatures. The analysis on predicted fuel cell power enhancement, TEG power generation and waste heat utilization were performed by relating the temperature profiles of the hydrogen reactant and TEG surfaces to fuel cell reaction models and TEG power relationships. A compact IHR design that produced 7.7 to 8 % total power enhancement and suitable in size for a mini FCV was identified for future development works

Performance of Single Cell and Double Stacked Thermoelectric Generator Modules for Low Temperature Waste Heat Recovery

“…The waste heat temperature (Twh) applied to the system are 53⁰C and 58⁰C [20]. Forced convection is applied to the cooling section at 21⁰C, with a speed of 10 m/s, referring to the cruising speed of a FCV [15,18]. This condition creates temperature difference between the surfaces of TEG for electrical power generation.…”

“…The fuel cell itself is a technology for combined heat and power (CHP) generation as it converts chemical energy into electricity as well as releases heat as by-product from the hydrogen-oxygen reaction [17]. The excess heat needs to be removed to avoid overheating of the membrane [18]. The potential carried by the waste heat requires effective energy conversion technology to fully utilize and convert it into useful electrical energy.…”