University of Hertfordshire


  • Xiangkui Gao
  • Yanping Yuan
  • Hongwei Wu
  • Xiaoling Cao
  • Xudong Zhao
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Original languageEnglish
Pages (from-to)370-381
Number of pages12
JournalSustainable Cities and Society
Early online date10 Jan 2018
Publication statusPublished - 1 Apr 2018


The coupled cooling method combining latent heat thermal energy storage and pre-cooling of the envelope (PE) is a new free-cooling method that is suitable for exposure to high temperatures and other types of harsh environments. PE plays the most critical role in the coupled cooling method. Long-term, continuous PE cannot only reduce energy storage capacity, but it also causes numerous energy waste. Thus, an intermittent operational mode is firstly proposed to improve the heat transfer performance and reduce energy consumption. A simplified numerical model of intermittent thermal storage is established, and the subsequent effects of intermittent ratio (IR) and intermittent period (IP) on cold storage performance have been systematically investigated. Furthermore, the operational period is divided into a cold storage period (CSP) and a cold preservation period (CPP), each with their own respective evaluation indices. Long-term intermittent PE is optimized, and an interchanging continuous/intermittent cold storage strategy is proposed. Under the current operating conditions, as compared with the conventional continuous mode, the duration of CSP is extended by 0–26%, yielding an annual cold storage energy consumption reduction of 68–78%. Thus, the current study demonstrates the significant potential of intermittent operational mode application in underground thermal energy storage systems.


This document is the Accepted Manuscript version of the following article: Xiangkui Gao, Yanping Yuan, Hongwei Wu, Xiaoling Cao, and Xudong Zhao, ‘Coupled cooling method and application of latent heat thermal energy storage combined with pre-cooling of envelope: Optimization of pre-cooling with intermittent mode’, Sustainable Cities and Society, Vol. 38: 370-381, April 2018. Under embargo until 10 January 2019. The final, definitive version of this paper is available online via:

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