Greenhouse heating using heat pumps with a high coefficient of performance (COP)

Tong, Yen Wah; Kozai, Toyoki; Nishioka, Nobuyasu; Ohyama, Katsumi

doi:10.1016/j.biosystemseng.2010.05.003

Cited by 79 publications

(29 citation statements)

References 22 publications

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“…Figure 3 shows the relationship between the daily number of reverse cycle defrostings and COP air . The daily number of reverse cycle defrostings ranged from 0 to 44, and COP air decreased as the daily number of reverse cycle defrostings increased, which is consistent with previous reports (Tong et al, 2010;Sasaki, 1989). Tong et al (2010) indicated that COP values were affected by T out and relative humidity, as well as the frequency and duration of reverse cycle defrosting.…”

Section: Operating Characteristics Of the Ashpsupporting

confidence: 80%

“…The daily number of reverse cycle defrostings ranged from 0 to 44, and COP air decreased as the daily number of reverse cycle defrostings increased, which is consistent with previous reports (Tong et al, 2010;Sasaki, 1989). Tong et al (2010) indicated that COP values were affected by T out and relative humidity, as well as the frequency and duration of reverse cycle defrosting. Although the frequency and duration of reverse cycle defrosting are not described in this paper, values were reported by Furuno et al (2012) for the same ASHP as that used here.…”

Section: Operating Characteristics Of the Ashpsupporting

confidence: 80%

“…Although several studies have examined the effects of outside field conditions on the COP of ASHPs, most have been conducted in the Kanto region, which has a warmer climate than that of Hokkaido and Tohoku. For example, Tong et al (2010) and Sasaki (1989) investigated the COP of ASHPs in Chiba and Kanagawa Prefecture, respectively. Few studies have been carried out to investigate the performance of ASHPs in colder and snowy areas.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of coefficient of performance (<i>COP</i>) between an underground water source heat pump system and an air source heat pump system for greenhouse heating in cold and snowy areas in Japan

Furuno

Okushima

Sase

2016

J. Agric. Meteorol.

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With the increasing cost of fossil fuels, the use of air source heat pumps (ASHPs) for greenhouse heating has become widespread in Japan. In general, the coefficient of performance (COP) of a ASHP depends on the outside air conditions, while the same is not expected for an underground water source heat pump (UWS-HP) system. Few studies have examined these comparisons in colder regions. In the present study, a UWS-HP system is developed, and the COPs of a UWS-HP (COP uws ) and a ASHP (COP air ) for use in greenhouse heating are investigated. The key results of the study can be summarized as follows: 1) COP uws ranged from 4.0 to 5.7 and had an average value of 4.9. COP uws was generally higher than COP air regardless of the outside temperature. 2) COP air ranged from 2.2 to 4.5 and had an average value of 3.4. Using the average hourly heat transfer coefficient obtained from the analysis of the UWS-HP, COP air was found to decrease with decreasing outside temperature. 3) COP air decreased with increasing frequency of the reverse cycle defrosting. 4) COP uws was not affected by the outside temperature, and inlet and outlet water temperature was approximately 1℃ and 11.5℃ respectively.

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Section: Operating Characteristics Of the Ashpsupporting

confidence: 80%

Section: Operating Characteristics Of the Ashpsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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Comparison of coefficient of performance (<i>COP</i>) between an underground water source heat pump system and an air source heat pump system for greenhouse heating in cold and snowy areas in Japan

Furuno

Okushima

Sase

2016

J. Agric. Meteorol.

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“…The demand for district heating is more or less constant whilst that for cooling has increased significantly in recent years: it has doubled in Sweden in the past 10 years [1]. Today's electrically powered heat pumps for producing cooling are highly efficient, with a coefficient of performance (COP) > 4 [2]. However, they are driven by a high-quality form of energy, i.e.…”

Section: Introductionmentioning

confidence: 99%

Co-production of pyrolysis oil and district cooling in biomass-based CHP plants: Utilizing sequential vapour condensation heat as driving force in an absorption cooling machine

Karlsson

Nilsson

2015

Applied Thermal Engineering

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“…The study of this paper is based on solar heat collection heating system, which turn the clean energy solar energy into the energy of the water of the pipes underground through the heat exchanger in daytime, and when the hot water reaches the set heating temperature, it will be carried to the pipeline of the greenhouse, which will heat the greenhouse [4] [5].…”

Section: Introductionmentioning

confidence: 99%

Numerical Modelling of Radiation-Convection Coupling of Greenhouse Using Underfloor Heating

Yan¹,

Wang²,

Zhang³

et al. 2017

OJFD

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Greenhouse is an important place for crop growth, and it is necessary to control the temperature of growing environment in winter. In addition, the root temperature underground also plays a decisive role for plants growth. Adopting underground heating to increase the temperature can effectively improve the yield of crops. The objective of our study was to model the heat transfer of greenhouse underfloor heating which is analyzed and simplified based on the FLUENT software by changing the several important factors that affect the temperature distribution: pipe diameter, pipe spacing, laying depth, supplied water temperature and flow rate, as boundary conditions to simulate the changes of the soil temperature field around the winter night environment. Researching the temperature distribution of the greenhouse, the soil surface and the plant root layer under the different parameters and the basic rules of the heating system are summarized. The results show that the water supply temperature, pipe spacing and diameter of the pipe has a greater impact on the ground and room temperature, and the laying depth has greater impact on the temperature uniformity of the ground, the velocity of water in pipe has little impact on the uniformity of ground temperature.

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Greenhouse heating using heat pumps with a high coefficient of performance (COP)

Cited by 79 publications

References 22 publications

Comparison of coefficient of performance (<i>COP</i>) between an underground water source heat pump system and an air source heat pump system for greenhouse heating in cold and snowy areas in Japan

Comparison of coefficient of performance (<i>COP</i>) between an underground water source heat pump system and an air source heat pump system for greenhouse heating in cold and snowy areas in Japan

Co-production of pyrolysis oil and district cooling in biomass-based CHP plants: Utilizing sequential vapour condensation heat as driving force in an absorption cooling machine

Numerical Modelling of Radiation-Convection Coupling of Greenhouse Using Underfloor Heating

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