Waste Heat Recovery via Thermoelectric Generation in a Natural Gas Engine: Numerical Modeling and Baseline Analysis

Ratnak Sok*, Jin Kusaka, Hisaharu Nakashima, Hidetaka Minagata

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

Abstract

The thermoelectric generator (TEG) can recover a fraction of exhaust energy loss from the automotive exhaust gas. However, its application is limited due to the pumping losses and turbocharger efficiency drop when the engine system is equipped with the TEG. This research aims to optimize the thermal efficiency of a compressed natural gas engine (CNG) system with the TEG mounted after a turbocharger via numerical modeling. The total engine model with the integrated thermoelectric module (TEM) and heat exchanger is developed in a commercial simulation tool. Measured data from the corrugated fin type heat exchanger TEG experiments under different fin pitches, gas temperatures, and mass flow rates are used for validating the TEG model. The TEG's heat exchanger modeling considers pressure differences at inlet and outlet, heat transfer coefficients from gas to wall, exchanger wall temperature, and the module heat flux. The model can predict the module's pressure loss and heat transfer characteristics. Next, the TEG model is integrated into a production type 3.0 L CNG engine model operated under spark ignition mode. The engine model was well calibrated with various measured data taken from a turbocharged, mass-production engine used in light-duty delivery CNG trucks. The effectiveness of the integrated engine and TEG model is demonstrated by focusing on engine brake thermal efficiency enhancement using waste heat recovery via thermoelectric generation. Finally, the engine system's thermal efficiency could be improved by up to 0.8 % without significant brake power loss.

Original languageEnglish
Pages (from-to)1395-1404
Number of pages10
JournalProceedings of the Thermal and Fluids Engineering Summer Conference
Volume2022-May
Publication statusPublished - 2022
Event7th Thermal and Fluids Engineering Conference, TFEC 2022 - Las Vegas, United States
Duration: 2022 May 152022 May 18

Keywords

  • Heat Exchanger
  • Natural Gas Engine
  • Thermo-Electric Generation
  • Waste Heat Recovery

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Electrical and Electronic Engineering

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