Determination of the optimal defrosting initiating time point for an ASHP unit based on the minimum loss coefficient in the nominal output heating energy

Wei Wang, Shiqiang Zhang, Zhaoyang Li, Yuying Sun, Shiming Deng, Xu Wu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)

Abstract

When an air source heat pump (ASHP) is operated at frosting conditions, controlling its defrosting initiation is very important, which affects its operating efficiency and output heating capacity. Therefore, to improve the accuracy of defrosting initiation of ASHPs under frosting-defrosting operations, an investigation on determination of an optimal defrosting initiating time point (topt) for an ASHP unit based on the minimum loss coefficient in the nominal output heating energy (εNLmin) has been carried out and the investigation results are presented in this paper. Firstly, the existence of topt was verified through a field study. Secondly, the development of multiple-variable-nonlinear models for predicting εNLmin and topt is detailed. Finally, the results of a related modeling study using the developed multiple-variable-nonlinear model for topt is presented. The results from the investigation suggested that initiating defrosting for an ASHP unit at topt could result in the best possible operating performances under its frosting-defrosting operations. It was further demonstrated through the modeling study that at a fixed ambient relative humidity, an increase in ambient air temperature would lead to a decreasing-increasing variation trend in topt, and at a fixed ambient air temperature, topt was decreased with an increase in relative humidity.

Original languageEnglish
Article number116505
JournalEnergy
Volume191
DOIs
Publication statusPublished - 15 Jan 2020

Keywords

  • ASHP units
  • Frosting and defrosting
  • Loss coefficient in the nominal output heating energy
  • Multiple-variable-nonlinear model
  • Optimal defrosting initiating time point

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Pollution
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

Cite this