Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

Gerald Englmair, Christoph Moser, Simon Furbo, Mark Dannemand, Jianhua Fan

Research output: Contribution to journalArticleResearchpeer-review

Abstract

A solar heating system with 22.4 m2 of solar collectors, a heat storage prototype consisting of four 200 kg phase-change material (PCM) storage units, and a 735 L water tank was designed to improve solar heat supply in single-family houses. The PCM storage utilized stable supercooling of sodium acetate trihydrate composites to conserve the latent heat of fusion for long-term heat storage. A control strategy directed heat from a solar collector array to either the PCM storage or a water buffer storage. Several PCM units had to be charged in parallel when the solar collector output peaked at 16 kW. A single unit was charged with 27.4 kWh of heat within four hours on a sunny day, and the PCM temperature increased from 20 °C to 80 °C. The sensible heat from a single PCM unit was transferred to the water tank starting with about 32 kW of thermal power after it had fully melted at 80 °C. A mechanical seed crystal injection device was used to initialize the crystallisation of the sodium acetate trihydrate after it had supercooled to room temperature. The unit discharge during solidification peaked at 8 kW. Reliable supercooling was achieved in three of the four units. About 80% of latent heat of fusion was transferred from PCM units after solidification of supercooled sodium acetate trihydrate to the water tank within 5 h. Functionality tests with practical operation conditions on the novel, modular heat-storage configuration showed its applicability for domestic hot water supply and space heating.

Original languageEnglish
Pages (from-to)522-534
Number of pages13
JournalApplied Energy
DOIs
Publication statusPublished - 1 Jul 2018

Fingerprint

supercooling
Supercooling
Solar heating
Heat storage
Phase change materials
acetate
Sodium
sodium
Water tanks
Solar collectors
Latent heat
solidification
Solidification
Fusion reactions
Buffer storage
water
Space heating
thermal power
solar heating
material

Keywords

  • Heat storage prototype
  • Phase change material
  • Sodium acetate trihydrate
  • Solar heating system
  • Stable supercooling

ASJC Scopus subject areas

  • Building and Construction
  • Energy(all)
  • Mechanical Engineering
  • Management, Monitoring, Policy and Law

Cite this

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system. / Englmair, Gerald; Moser, Christoph; Furbo, Simon; Dannemand, Mark; Fan, Jianhua.

In: Applied Energy, 01.07.2018, p. 522-534.

Research output: Contribution to journalArticleResearchpeer-review

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