Derivation of guidelines for the design of plate evaporators in heat pumps using zeotropic mixtures

Brian Elmegaard, Roberta Mancini, Benjamin Zühlsdorf

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Abstract

The present work derives design recommendations for plate heat exchangers used for evaporation of zeotropic mixtures in heat pumps. A parametric study is conducted on the geometry of the heat exchanger, and the analysis is carried out for four working fluids, based on a case study of heat pump integration in a spray drying facility. A numerical model of the evaporator is combined with cycle calculations, for estimating the impact of heat transfer area and pressure drop on the coefficient of performance and costs. Common trends are obtained as optimal configurations for the four considered fluids. It is recommended to minimize the hydraulic diameter by employing high corrugation height over low corrugation pitch. Moreover, an optimal range is found for the liquid Reynolds number at the evaporator inlet. The suggested values vary between 500 and 2000, depending on the fluid. Lastly, the trade-off between minimization of area and pressure drop is found by assessing the relative impact on costs of the heat exchanger area and pressure losses of both working fluid and heat source. The result shows that it is not always convenient to minimize the heat transfer area, since the mixture pressure drop negatively influences compressor investment and operating costs.
Original languageEnglish
Title of host publicationProceedings of ECOS 2017: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
Number of pages17
Publication date2017
Publication statusPublished - 2017
Event30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems - The Conrad Prebys Aztec Student Union, San Diego State University 6075 Aztec Cir Dr, San Diego, United States
Duration: 2 Jul 20176 Jul 2017
Conference number: 30
http://www.ecosconference.org/

Conference

Conference30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
Number30
LocationThe Conrad Prebys Aztec Student Union, San Diego State University 6075 Aztec Cir Dr
CountryUnited States
CitySan Diego
Period02/07/201706/07/2017
Internet address

Keywords

  • Plate heat exchangers
  • Waste heat recovery
  • Zeotropic mixtures
  • Heat pumps
  • Cost optimization

Projects

THERMCYC: Advanced thermodynamic cycles utilising low-temperature heat sources

Elmegaard, B., Haglind, F., Clausen, L. R., Kærn, M. R., Markussen, W. B., Sin, G., Gani, R., Meroni, A., Andreasen, J. G., Cignitti, S., Frutiger, J., Babi, D. K., Sørensen, I., Pierobon, L., Zhang, L., Zühlsdorf, B. & Mancini, R.

01/03/201428/02/2019

Project: Research

Cite this

Elmegaard, B., Mancini, R., & Zühlsdorf, B. (2017). Derivation of guidelines for the design of plate evaporators in heat pumps using zeotropic mixtures. In Proceedings of ECOS 2017: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems