Direct Contact Latent Heat Storage for Efficiency Enhancement of Heat Pumps

Abstract

Direct Contact Latent Heat Storage for Efficiency Enhancement of Heat PumpsWith an innovative concept for the storage of thermal energy at low and constant temperature levels, solar thermal energy can be used effectively in transition and winter periods. Furthermore, the solar energy can be stored to increase the efficiency of heat pumps. A latent heat storage system based on salt hydrates is introduced, where the salt hydrate has a melting point of 15°C and is in direct contact with an immiscible heat transfer fluid generating a high charging and discharging capacity. Initial experimental results and application examples are presented and discussed.

Ausgleich der Volatilität der Erneuerbaren Energien mittels Wärmespeichern auf Salzbasis

“…Konzepte für den Niedertemperaturbereich mit dem Gemisch Paraffin und Wasser aber auch mit Salzhydraten [10] sind bekannt.…”

Channel formation and visualization of melting and crystallization behaviors in direct‐contact latent heat storage systems

“…Further studies on direct‐contact latent heat storage systems are described in the literature . In these studies, only a few simplified descriptions of the melting and crystallization behaviors are given .…”

“…F I G U R E 1 Schematic illustration of a direct-contact latent heat storage system 15 In this study, a direct-contact latent heat storage system employing a eutectic mixture of two salt hydrates as the PCM, namely, magnesium chloride hexahydrate and magnesium nitrate hexahydrate, and a mineral oil as the HTF is investigated. Figure 1 illustrates a direct-contact latent heat storage tank.…”

“…• Higher charging and discharging rates due to improved heat transfer between the PCM and the HTF • Higher storage density, since there is no piping system in the storage tank • Extended period of high transfer rate during charge because solidified PCM with low thermal conductivity around the piping system does not screen the heat transfer Further studies on direct-contact latent heat storage systems are described in the literature. 14,15,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] In these studies, only a few simplified descriptions of the melting and crystallization behaviors are given. 34,36 In particular, the determination of heat transfer surfaces has not been described.…”

Vergleich dreier Latentwärmespeicherkonzepte zur effizienten Nutzung von Niedertemperaturwärme

“…Trotz hoher Speicherdichten von bis zu 500 kWh m -3 besitzen thermochemische Speicher den Nachteil, dass die Technologie bisher meist nicht ausge-reift und komplex ist [1]. Im Vergleich zu sensiblen Speichern besitzen Latentwärmespeicher, die im Unterschied zu sensiblen Speichern während der Energiespeicherung den Aggregatzustand wechseln, folgende Vorteile [ [10].…”