Experimental investigation on the thermal performance of a qanat-source heat pump. (January 2021)

• Record Type: Journal Article
• Authors: Delfani, Shahram; Esmaeelian, Jafar; Karami, Maryam
• Is Part Of: Geothermics. Volume 89(2021)
• Publication Date: 2021-01
• Subjects: EER energy efficiency ratio -- COP coefficient of performance -- GWHP ground water heat pump -- QSHP qanat-source heat pump -- ASHP air-source heat pump -- HP heat pump -- RH relative humidity; Geothermal -- Water source heat pump (WSHP) -- Heating and cooling -- Qanat; Hydrogeology -- Periodicals; Geothermal resources -- Periodicals; Énergie géothermique -- Périodiques; GEOTHERMAL ENGINEERING; GEOTHERMAL ENERGY; GEOTHERMAL EXPLORATION; Geothermal resources; Hydrogeology; Periodicals; Electronic journals; 621.44
• DOI: 10.1016/j.geothermics.2020.101933
• Languages: English
• ISSNs: 0375-6505

Abstract

Highlights: The thermal performance of a qanat source heat pump (QSHP) is experimentally investigated. Due to the stable qanat water temperature, the QSHP has the constant efficiency during the year. The QSHP has the EER of on average 3.74 in cooling mode and the COP of an average 3.88 in heating mode. The COP of the air-source heat pump fluctuates 9 %, while the COP of the QSHP varies only 1.5 %. Abstract: In this paper, the thermal performance of a heat pump connected to the qanat has been experimentally investigated in both heating and cooling modes. For this purpose, a test site consisting of a heat pump, a coil submerged in the qanat and the measuring and monitoring equipment was designed, constructed and tested. A conventional air-source heat pump system was also used for comparison of the heat pump performance with different heat sources/sinks. Results showed that the efficiency of the air-source heat pump is strongly influenced by environmental conditions, whereas the efficiency of the qanat-source heat pump is very stable and has a good performance throughout the year. In the cooling mode, the energy efficiency ratio (EER) of the qanat-source heat pump varied from 3.77 to 3.7, changing 1.8 %, while the EER of the air-source system fluctuated between 3.14 and 2.95, indicating a 6 % decline. In heating mode, the qanat-source system was also very stable, with a 1.5 % variation in the coefficient of performance (COP) from 3.85 to 3.91, while the COP of the air-source system fluctuated between 3.37 and 3.05, indicating a 9 % change, because of the high fluctuations of the ambient temperature in the heating season in the test site location. The results revealed that the system can be used as an energy-efficient and sustainable alternative to conventional heating and air conditioning systems.