An Experiment on Heat Recovery Performance Improvements in Well-Water Heat-Pump Systems for a Traditional Japanese House

Chiemi Iba,Shun Takano,Shuichi Hokoi

doi:10.3390/en11051023

Abstract

Concerns about resource depletion have prompted several countries to promote the usage of renewable energy, such as underground heat. In Japan, underground heat-pump technology has begun to be utilized in large-scale office buildings; however, several economic problems are observed to still exist, such as high initial costs that include drilling requirements. Further, most of the traditional dwellings “Kyo-machiya” in Kyoto, Japan have a shallow well. This study intends to propose an effective ground-source heat-pump system using the well water from a “Kyo-machiya” home that does not contain any drilling works. In previous research, it was depicted that the well-water temperature decreases as the heat pump (HP) is operated and that the heat extraction efficiency steadily becomes lower. In this study, an experiment is conducted to improve efficiency using a drainage pump. Based on the experimental results, the effect of efficiency improvement and the increase in the electric power consumption of the drainage pump are examined. It is indicated that short-time drainage could help to improve efficiency without consuming excessive energy. Thus, continuous use of the heat pump becomes possible.

Highlights

Many countries have promoted the use of renewable energy to overcome environmental issues, such as resource depletion and global warming
In 2017–2018, as shown in Figure 4b, the heat recovery operation started after terminating the heat pump operation for a few days
A heat recovery experiment was conducted to examine the improvement in the heat recovery performance by forced drainage of the well water

Summary

Introduction

Many countries have promoted the use of renewable energy to overcome environmental issues, such as resource depletion and global warming. One form of renewable energy, known as underground heat, is a consistently available energy source that has been mainly utilized so far as a part of heat-pump systems [1,2]. In Japan, underground heat-pump technology has begun to be utilized in large-scale office buildings, and further applications for the technology are expected to emerge [3,4,5]. It has been reported that this type of heat exchanger can be effectively utilized even in the greenhouse crop industry, which requires large amounts of energy for heating [8]

Objectives

Methods

Results

Discussion

Conclusion