Heat Exchanger Sizing for Organic Rankine Cycle

Abstract

Approximately 45% of power generated by conventional power systems is wasted due to power conversion process limitations. Waste heat recovery can be achieved in an Organic Rankine Cycle (ORC) by converting low temperature waste heat into useful energy, at relatively low-pressure operating conditions. The ORC system considered in this study utilises R-1234yf as the working fluid; the work output and thermal efficiency were evaluated for several operational pressures. Plate and shell and tube heat exchangers were analysed for the three sections: preheater, evaporator and superheater for the hot side; and precooler and condenser for the cold side. Each heat exchanger section was sized using the appropriate correlation equations for single-phase and two-phase fluid models. The overall heat exchanger size was evaluated for optimal operational conditions. It was found that the plate heat exchanger out-performed the shell and tube in regard to the overall heat transfer coefficient and area.

Waste Heat Recovery from Diesel Engine Exhaust Using a Single-Screw Expander Organic Rankine Cycle System: Experimental Investigation of Exergy Destruction

“…The stringent local and international limits on the exhaust emission of pollutant gases, such as CO, NOx, CO 2 , particulate matter, and other hydrocarbons, have rekindled interest in the development of energy-efficient and cleaner propulsion system for vehicles [1]. Moreover, reduction of the fuel consumption and the amount of greenhouse gases whilst increasing the mechanical performance of ICEs has been the focal point of research in the automotive sector [2]. In ICEs, only about 1/3 of the input fuel energy is converted into useful power [3]; the remainder, amounting to almost 40%, is wasted from the engine exhaust [4].…”