Experimental study of an instantaneous-heating air source heat pump water heater with a temperature stratified water tank

Lei, Mingjing; Zhang, Hua; Wang, Fang; You, Xiaokuan

doi:10.1177/1687814016671248

Cited by 10 publications

(5 citation statements)

References 10 publications

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“…These results could represent HPWH performance trends when coupled with a water-based solar collector to preheat the inlet water if the electric source in the study were replaced with a solar collector. The research by Bursill et al also showed an increase in performance of HPWH systems as the HPWH water temperature set point decreases, which is representative of other research in the field [16].…”

Section: Heat Pump Water Heaterssupporting

confidence: 54%

“…However, a lower limit on the storage tank temperature of 49⁰C is required by the Canadian government to prevent growth of legionella bacteria. Lei et al [16] conducted experiments on an instantaneous HPWH and found that instantaneous HPWHs could achieve a COP as high as 12.6. This is because instantaneous water heaters are tankless which mitigates the risk of legionella, allowing low temperature setpoints to be used thus eliminating the energy consumption that tank water heaters use to reach higher temperatures.…”

Section: Heat Pump Water Heatersmentioning

confidence: 99%

“…16, respectively. The subsidy values shown are the subsidy that would have to be introduced for a HPWH or SAHPWH to have the same LCC as the alternative water heating methods given the current capital costs of HPWHs or SAHPWHs.…”

mentioning

confidence: 97%

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Technoeconomic Analysis of Air Based Solar Assisted Heat Pump Water Heaters for Canadian and American Cities

Treichel¹

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Heat pump water heaters (HPWHs) have limited market share in Canada and the United States largely due to their space cooling effect which increases heating costs throughout winters in these countries. Coupling a HPWH with solar collectors lessens the space cooling effect during cold-climate heating seasons while also improving HPWH performance year-round in cold and moderate climates. This study experimentally and numerically examined air-based solar collectors and their impact on HPWHs with the objective of determining the feasibility of solar assisted HPWHs in residential detached dwellings in Canada and the United States. An air-based solar collector was added to an experimentally validated HPWH model, and different configurations of solar-assisted HPWH (SAHPWH) were analyzed to determine their energy performance, greenhouse gas emissions (GHGs), and various economic parameters. The results indicate that the space

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Section: Heat Pump Water Heaterssupporting

confidence: 54%

Section: Heat Pump Water Heatersmentioning

confidence: 99%

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Technoeconomic Analysis of Air Based Solar Assisted Heat Pump Water Heaters for Canadian and American Cities

Treichel¹

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“…Temperature stratification majorly determines the performance of a water-based thermal storage system. 2,3 The peak-load reduction effect of the storage tank can be further increased by precisely controlling the temperature stratification in the storage tank. The ideal stratification maximizes the energy efficiency of a heat storage tank.…”

Section: Introductionmentioning

confidence: 99%

Temperature stratification using an air-cooled heat pump system with a mixing valve

Han

Kim

Lim

et al. 2014

Advances in Mechanical Engineering

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The main factor determining the performance of a thermal storage method is the temperature stratification in the storage tank. At the ideal stratification, the energy efficiency of the storage tank is extremely high. However, when the heat pump is applied, the stratification is disrupted by heat exchange between the layers of the heat medium, and consequent convection in the tank. Therefore, this study analyzed the influence of stratification-related design factors in the water-piping facility area outside a tank heated by a heat pump. In particular, it assessed the thermal stratification and energy efficiency in the storage tank installed with a mixing valve. In the system using the mixing valve, hot water of constant temperature was supplied to the top of the storage tank, reducing the mixing effect of the hot and cold waters; consequently, the stratification index was maximized at 0.42. Comparing the times at which the temperature of the uppermost part reached 70°C in the systems with and without the mixing valve (30 and 75 min, respectively), we find that the mixing valve reduced the time of obtaining effectively hot water by approximately 60%.

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“…Lei et al [19] designed and tested an instantaneous-heating air source heat pump water heater (IASHPWH) with a temperature stratified tank, using R410A refrigerant. The IASHPWH operated using three modes: condenser heating for a source temperature over 20 o C, water tank heating for a source temperature below 20 o C and condenser-water tank joint heating.…”

Section: Heat Pump Technologymentioning

confidence: 99%

Experimental Characterization and Modelling of a Heat Pump Water Heater

Khalaf¹

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Canada plays a leading role in the initiative to divert energy sources from greenhouse gas (GHG) emissive power sources to renewable and sustainable energy sources. Through the Clean Energy Act, Canada is subjected to introduce a reduction in electricity demand by 66%, and GHG emission reduction by 80%, from the levels achieved in 2007, by 2020. This thesis investigated the use of heat pump water heater technology to assist in the reduction of GHG emissions and energy in domestic water heating for the residential sector. Heat pump water heaters (HPWHs) have had great success in the warm, humid climates of the US, Europe and Asia. However, due to the longer heating season in Canada, a conventional HPWH installed in a residential basement can increase the space heating demand in the winter. Models have been used to study heat pumps and thermal storage as separate components. However, few modelling studies have been conducted on HPWHs with condensers as wrap-around coils on the outside wall of the water storage tank. This study involved the development of a new HPWH model in the TRNSYS simulation software, based on Types 938 (heat pump water heater) and 534 (water storage tank), to investigate the effect of a HPWH unit on the space heating and cooling requirements of a house. The model was verified by experiment using a commercially available HPWH unit in a laboratory setting. The experimental set-up consisted of an air-source heat pump connected to a controlled air supply that provided constant temperature, flow rate, relative humidity to the unit, as well as a draw system for hourly water draws. A performance map was experimentally obtained through monitoring the air temperature, relative humidity, and water temperature as the independent variables, while the total and sensible cooling capacity, compressor power and heat delivery were the dependent variables. The result of the study showed that humidity has a negative effect on the performance of the unit at low temperatures. I would like to thank my supervisor, Dr. Cynthia Cruickshank, for the support, guidance, and patience she has provided for the last 2 years. I would like to thank my colleagues within the Solar Energy Systems Laboratory who have provided friendship, guidance, and mentorship over the duration of my thesis. These people include, but are not limited to,

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Experimental study of an instantaneous-heating air source heat pump water heater with a temperature stratified water tank

Cited by 10 publications

References 10 publications

Technoeconomic Analysis of Air Based Solar Assisted Heat Pump Water Heaters for Canadian and American Cities

Technoeconomic Analysis of Air Based Solar Assisted Heat Pump Water Heaters for Canadian and American Cities

Temperature stratification using an air-cooled heat pump system with a mixing valve

Experimental Characterization and Modelling of a Heat Pump Water Heater

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