An experimental comparison of two heat exchangers used in wastewater source heat pump: A novel dry-expansion shell-and-tube evaporator versus a conventional immersed evaporator

Chao Shen, Yiqiang Jiang, Yang Yao, Xinlei Wang

Research output: Contribution to journalArticlepeer-review

Abstract

A novel dry-expansion shell-and-tube evaporator (DESTE) integrated with function of defouling was developed as a component of wastewater source heat pump (WWSHP). To compare the performance of the DESTE-WWSHP with the conventional immersed evaporator (IE) based wastewater source heat pump (IE-WWSHP), an experimental platform was built by installing a DESTE and an IE unit in parallel in a same WWSHP system. The performance tests were conducted with the wastewater collected from downstream of a commercial sauna center in Shenzhen, China. Several operating parameters were investigated, including water heating capacity, coefficient of performance (COP), hot water temperature settings, wastewater discharge rate/pattern, and hot water discharge mode (continuous or intermittent). Results showed that the DESTE-WWSHP delivered comparable heat transfer performance to the IE-WWSHP, and thus, could serve as a replacement for the latter design. Specifically, the water temperature in the water storage tank was more uniformly distributed in the DESTE-WWSHP than the IE-WWSHP; the DESTE-WWSHP exhibited higher water heating capacity than the IE-WWSHP in the continuous hot water discharge mode. The DESTE has a heat transfer coefficient 3.1 times higher than that of the IE unit on the wastewater side. At the same heating capacity, the DESTE was far more compact with its compactness 7 times higher and its volume 91.71% smaller than the IE unit, leading to considerable savings in room space and materials. Additional benefits offered by this DESTE-WWSHP included reduced labor and power costs for cleaning heat exchanger, and decreased odor nuisance.

Original languageEnglish (US)
Pages (from-to)600-608
Number of pages9
JournalEnergy
Volume47
Issue number1
DOIs
StatePublished - Nov 2012

Keywords

  • Dry-expansion
  • Immersed evaporator
  • Shell-and-tube evaporator
  • Wastewater source heat pump
  • Water heating

ASJC Scopus subject areas

  • Mechanical Engineering
  • General Energy
  • Pollution
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering
  • Management, Monitoring, Policy and Law
  • Industrial and Manufacturing Engineering
  • Building and Construction
  • Fuel Technology
  • Renewable Energy, Sustainability and the Environment
  • Civil and Structural Engineering
  • Modeling and Simulation

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