On the effects of increased coolant temperatures of light duty engines on waste heat recovery

Research output: Contribution to journalArticle

Abstract

In this paper, an investigation is done into the potential of increasing the coolant temperature of an engine to maximize the powertrain efficiency. The study takes a holistic approach by trying to optimise the combined engine and waste heat recovery system. The work was done experimentally on a Volvo 4-cylinder light duty diesel engine in combination with Rankine cycle simulations. For the study, the coolant temperature was swept from 80 °C to 160 °C at different operating points. It was seen that with increased coolant temperatures, the brake efficiency of the engine increased by up to 1 percentage point due to reduced heat losses. An optimum coolant temperature was observed, dependent on the operating point, for maximizing coolant recoverable power. An expansive study was done simulating 48 working fluids for a dual loop waste heat recovery system. From the working fluids simulated, cyclopentane was seen as the best for coolant waste heat recovery, whereas methanol and acetone were better for the exhaust gases. The gain in efficiency seen, was up to 5.2 percentage points, with up to 1.7 percentage points as the effect due to recovered power from the coolant.

Details

Authors
Organisations
External organisations
  • Chalmers University of Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering

Keywords

  • Elevated coolant temperatures, Light duty engine, Low temperature waste heat recovery, Rankine cycle, Recoverable power, Reduced heat losses
Original languageEnglish
Article number115157
JournalApplied Thermal Engineering
Volume172
Publication statusPublished - 2020 May 25
Publication categoryResearch
Peer-reviewedYes