Thermodynamic analysis of vapor compression heat pump cycle for tap water heating and development of CO2 heat pump water heater for residential use

Michiyuki Saikawa, Shigeru Koyama

    Research output: Contribution to journalArticle

    30 Citations (Scopus)

    Abstract

    The ideal vapor compression cycle for tap water heating and its coefficient of performance (COP) have been studied theoretically at first. The ideal cycle is defined as the cycle whose high temperature heat source varies temperature with constant specific heat and other processes are same as the reverse Carnot cycle. The COP upper limit of single stage compression heat pump cycle for tap water heating with various refrigerants such as fluorocarbons and natural refrigerants was calculated. The refrigerant which achieves the highest COP for supplying hot water is CO2. Next, the prototype of CO2 heat pump water heater for residential use has been developed. Its outline and experimental results are described. Finally its further possibility of COP improvement has been studied. The COP considered a limit from a technical point of view was estimated about 6.0 at the Japanese shoulder season (spring and autumn) test condition of heating water from 17 °C to 65 °C at 16 °C heat source air temperature (dry bulb)/12 °C (wet bulb).

    Original languageEnglish
    Pages (from-to)1236-1243
    Number of pages8
    JournalApplied Thermal Engineering
    Volume106
    DOIs
    Publication statusPublished - Aug 5 2016

    All Science Journal Classification (ASJC) codes

    • Energy Engineering and Power Technology
    • Industrial and Manufacturing Engineering

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