Analytical investigation of low temperature lift energy conversion systems with renewable energy source

Hoseong Lee, Yunho Hwang, Reinhard Radermacher

Research output: Contribution to journalArticlepeer-review


The efficiency of the renewable energy powered energy conversion system is typically low due to its moderate heat source temperature. Therefore, improving its energy efficiency is essential. In this study, the performance of the energy conversion system with renewable energy source was theoretically investigated in order to explore its design aspect. For this purpose, a computer model of n-stage low temperature lift energy conversion (LTLEC) system was developed. The results showed that under given operating conditions such as temperatures and mass flow rates of heat source and heat sink fluids the unit power generation of the system increased with the number of stage, and it became saturated when the number of staging reached four. Investigation of several possible working fluids for the optimum stage LTLEC system revealed that ethanol could be an alternative to ammonia. The heat exchanger effectiveness is a critical factor on the system performance. The power generation was increased by 7.83% for the evaporator and 9.94% for the condenser with 10% increase of heat exchanger effectiveness. When these low temperature source fluids are applied to the LTLEC system, the heat exchanger performance would be very critical and it has to be designed accordingly.

Original languageEnglish
Pages (from-to)92-99
Number of pages8
JournalApplied Thermal Engineering
Issue number1-2
Publication statusPublished - 2014 Jul
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by The Abell Foundation, Inc. and sponsors of the CEEE, University of Maryland, College Park, MD, USA .


  • Low temperature lift energy conversion
  • Multi-stage cycle
  • Power generation system

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering


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