Experimental study on Rankine cycle evaporator efficiency intended for exhaust waste heat recovery of a diesel engine

Nikolay Milkov,Christelle Perilhon,Plamen Punov,Pierre Podevin,Quentin Danel,Teodossi Evtimov

doi:10.1051/matecconf/201713304003

Abstract

The paper pressents an experimental study of Rankine cycle evaporator efficiency. Water was chosen as the working fluid in the system. The experimental test was conducted on a test bench equipped with a burner charged by compressed fresh air. Generated exhaust gases parameters were previously determined over the diesel engine operating range (28 engine operating points were studied). For each test point the working fluid parameters (flow rate and evaporating pressure) were varied. Thus, the enthalpy flow through the heat exchanger was determined. Heat exchanger was designed as 23 helical tubes are inserted. On the basis of the results, it was found out that efficiency varies from 25 % to 51,9 %. The optimal working fluid pressure is 20 bar at most of the operating points while the optimum fluid mass flow rate varies from 2 g/s to 10 g/s.

Highlights

Waste heat recovery by means of Rankine cycle is a promising approach for achieving significant reduction in fuel consumption and CO2 emissions of the vehicles
The efficiency of Rankine cycle strongly depends on the heat transfer in heat exchanger from exhaust gases to the working fluid
Results present the variation of the heat exchanger outlet exhaust gases temperature and outlet working fluid temperature as a function of the working fluid pressure

Summary

Introduction

Waste heat recovery by means of Rankine cycle is a promising approach for achieving significant reduction in fuel consumption and CO2 emissions of the vehicles. The efficiency of Rankine cycle strongly depends on the heat transfer in heat exchanger from exhaust gases to the working fluid. There are many types of heat exchangers depends on their design. As a function of flow direction they can be separated as: co-current and counter-current. The opposite direction of the fluids (counter-current) leads to higher efficiency. In order to select suitable heat exchanger many parameters have to be taken into account such as: heat exchange surface, operating pressure, operating temperature, mass flow rates, hydraulic losses, size, mass, price and etc. The higher heat exchange surface and the minimum heat exchange resistance are preferable

Methods

Results

Conclusion