scholarly journals Performance Analysis of Heat Pump Dryer with Unit-Room in Cold Climate Regions

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3125 ◽  
Author(s):  
Yuan ◽  
Lin ◽  
Mao ◽  
Li ◽  
Yang ◽  
...  
Keyword(s):  
Heat Pump ◽  
Ambient Air ◽  
Open Loop ◽  
Cold Climate ◽  
Coefficient Of Performance ◽  
Ambient Conditions ◽  
Total Energy Consumption ◽  
Ambient Temperatures ◽  
Moisture Extraction ◽  
Modelling System

This study presents the development and evaluation of a novel partially open-loop heat pump dryer with a unit-room (HPDU). The unit-room was designed to enable the ambient air to be mixed with the return air, thereby reducing the influence of the ambient air on the system performance, while maintaining a high system thermal efficiency. A modelling system for the HPDU was developed and validated based on a real-scale experimental study. By using the modelling system, the system characteristics under different ambient conditions and bypass factors were analyzed. The energy benefit of the proposed HPDU was quantified through a comparative study with a closed-loop heat pump dryer (CHPD). It is evident that a maximal specific moisture extraction rate (SMER) and a minimal total energy consumption (TEC) existed when changing the bypass factor of the HPDU under certain ambient temperatures. Compared to the CHPD, the coefficient of performance (COP) of the HPDU increased by up to 39.56%, presenting a significant energy benefit for the application of HPDU.

scholarly journals Theoretical Analysis of a Single-Stage Gas-fired Ejector Heat Pump Water Heater

2021 ◽  
pp. 1-28
Author(s):  
Jeremy Spitzenberger ◽  
Pengtao Wang ◽  
Laith Ismael ◽  
Hongbin Ma ◽  
Ahmad Abuheiba ◽  
...  
Keyword(s):  
Heat Pump ◽  
Thermal Energy ◽  
Ambient Air ◽  
Single Stage ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Capacity ◽  
Condenser Temperature

Abstract Ejector driven systems have the ability to operate at high efficiencies, utilizing recycled thermal energy as a power source. For a typical ejector heat pump system, the increase of the condenser temperature reduces the coefficient of performance (COP). In addition, if the condenser temperature is higher than the critical temperature, the ejector may not function. In this situation, the condenser temperature must be reduced, and an additional heater will be utilized to heat the production water from the condenser temperature to the desired temperature. In this investigation, a single-stage gas-fired ejector heat pump (EHP) is investigated and thermodynamically modeled in order to optimize the system COP for the purpose of heating water by utilizing the thermal energy from the ambient air. The effects of the high-temperature evaporator (HTE) and low-temperature evaporator (LTE) temperatures on the ejector critical back pressure and the EHP system performance are examined for a HTE temperature range of 120-180 °C and LTE temperatures of 15.5, 17.5, and 19.5 °C. Results show that an optimized COP of the EHP system exists which depends on HTE and LTE temperatures, primary nozzle throat diameters. In addition, it is found that the EHP COP is independent of the ejector COP. From this investigation a maximum EHP COP of 1.31 is able to be achieved for a HTE temperature of 160 °C and a LTE temperature of 19.5 °C with a total heating capacity of 15.98 kW.

Secondary Fluids for GAX Absorption Heat Pump

2003 ◽  
Author(s):  
G. Anand ◽  
C. B. Panchal ◽  
D. C. Erickson
Keyword(s):  
Los Angeles ◽  
Natural Gas ◽  
Heat Pump ◽  
Performance Model ◽  
Coefficient Of Performance ◽  
Pumping Power ◽  
Ambient Conditions ◽  
Absorption Heat Pump ◽  
Heating And Cooling ◽  
Secondary Fluid

The gas-fired Generator-Absorber heat eXchanger (GAX) heat pump is being considered for space conditioning in residential and light commercial applications. In order to meet the national building codes for ammonia absorption heat pumps, a secondary fluid is used to interface with the air-coils. Proper choice of a secondary fluid maximizes the economic advantage of the GAX heat pump. The secondary fluid transfers the heating and cooling loads from the absorption heat pump to and from outdoor and indoor air-coils. The physical properties of secondary fluids influence the heat transfer performance in the heat-exchange equipment and hence the effective lift, thereby determining the cycle coefficient of performance (COP). Additionally, the pumping power for each fluid varies depending on the density and viscosity at operating temperatures. The variation in cycle COP and pumping power as a result of fluid properties is ultimately manifested as changes in electric and natural-gas cost. An analysis was carried out to evaluate six secondary fluids for a GAX absorption heat pump. A performance model was developed to simulate the secondary-fluid flow loops and the absorption heat pump. The utility costs for heating and cooling were determined for a typical building. The effects of ambient conditions and local utility rates were determined by modeling the annual utility costs in four cities: Atlanta, Chicago, Los Angeles, and New York. These four cities provided wide variations in heating and cooling requirements, and utility rates for natural gas and electricity. The results from this study provide a basis for selecting secondary fluids for heat pumping in different locations.

scholarly journals Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 479
Author(s):  
Ignacio Paniagua ◽  
Ángel Álvaro ◽  
Javier Martín ◽  
Celina Fernández ◽  
Rafael Carlier
Keyword(s):  
Heat Pump ◽  
Thermodynamic Cycle ◽  
Heat Pumps ◽  
Design Tool ◽  
Operating Conditions ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Ambient Conditions ◽  
Water Heater ◽  
Water Heaters

Although CO 2 as refrigerant is well known for having the lowest global warming potential (GWP), and commercial domestic heat pump water heater systems exist, its long expected wide spread use has not fully unfolded. Indeed, CO 2 poses some technological difficulties with respect to conventional refrigerants, but currently, these difficulties have been largely overcome. Numerous studies show that CO 2 heat pump water heaters can improve the coefficient of performance (COP) of conventional ones in the given conditions. In this study, the performances of transcritical CO 2 and R410A heat pump water heaters were compared for an integrated nearly zero-energy building (NZEB) application. The thermodynamic cycle of two commercial systems were modelled integrating experimental data, and these models were then used to analyse both heat pumps receiving and producing hot water at equal temperatures, operating at the same ambient temperature. Within the range of operation of the system, it is unclear which would achieve the better COP, as it depends critically on the conditions of operation, which in turn depend on the ambient conditions and especially on the actual use of the water. Technology changes on each side of the line of equal performance conditions of operation (EPOC), a useful design tool developed in the study. The transcritical CO 2 is more sensitive to operating conditions, and thus offers greater flexibility to the designer, as it allows improving performance by optimising the global system design.

scholarly journals Heat Pump Water Heater For Cold Climate – Canada

2021 ◽  
Author(s):  
Afarin Amirirad
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Residential Buildings ◽  
Minimum Energy ◽  
Cold Climate ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Domestic Hot Water ◽  
Heat Pump Water Heater

Considering the large energy consumption of conventional water heaters in residential buildings, the performance of a new type of water heater has been characterized through conducting experiments and numerical modelling. The specific water heater investigated in this work benefits from heat absorption from the indoor air, denoted as the air source heat pump water heater (ASHPWH), and is located in the Archetype Sustainable Twin House B in Toronto. The experiments have been conducted under three different indoor conditions associated with temperature and humidity. The coefficient of performance (COP), which quantifies the ratio of heating capacity to the consumed power of ASHPWH, ranges between 1.5 and 5, depending on the indoor dry bulb and water inlet temperatures. A TRNSYS model of ASHPWH has been constructed based on the obtained experimental results and has subsequently been integrated with a TRNSYS model of the Archetype Sustainable House (ASH). The numerical results were verified with the experimental data. The model results suggests that after employing ASHPWH, the domestic hot water energy consumption reduces by 60.3% and 53.2% compared to the electric water heater in summer and winter respectively. Due to the energy absorption of ASHPWH from the indoor environment, the heating load of the ASH house increases while its cooling load decreases. Furthermore, the annual electricity consumption of the ASH house due to the required heating and cooling as well as the domestic hot water demand is reduced by 21.3%. Finally, as a consequence of employing ASHPWH, the energy cost and GHG emission were reduced respectively by 22% and 21.7%. By investigating the system in four other Canadian cities, it appears that Vancouver and Edmonton would have the maximum and minimum energy savings respectively.

scholarly journals Heat Pump Water Heater For Cold Climate – Canada

2021 ◽  
Author(s):  
Afarin Amirirad
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Residential Buildings ◽  
Minimum Energy ◽  
Cold Climate ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Domestic Hot Water ◽  
Heat Pump Water Heater

Considering the large energy consumption of conventional water heaters in residential buildings, the performance of a new type of water heater has been characterized through conducting experiments and numerical modelling. The specific water heater investigated in this work benefits from heat absorption from the indoor air, denoted as the air source heat pump water heater (ASHPWH), and is located in the Archetype Sustainable Twin House B in Toronto. The experiments have been conducted under three different indoor conditions associated with temperature and humidity. The coefficient of performance (COP), which quantifies the ratio of heating capacity to the consumed power of ASHPWH, ranges between 1.5 and 5, depending on the indoor dry bulb and water inlet temperatures. A TRNSYS model of ASHPWH has been constructed based on the obtained experimental results and has subsequently been integrated with a TRNSYS model of the Archetype Sustainable House (ASH). The numerical results were verified with the experimental data. The model results suggests that after employing ASHPWH, the domestic hot water energy consumption reduces by 60.3% and 53.2% compared to the electric water heater in summer and winter respectively. Due to the energy absorption of ASHPWH from the indoor environment, the heating load of the ASH house increases while its cooling load decreases. Furthermore, the annual electricity consumption of the ASH house due to the required heating and cooling as well as the domestic hot water demand is reduced by 21.3%. Finally, as a consequence of employing ASHPWH, the energy cost and GHG emission were reduced respectively by 22% and 21.7%. By investigating the system in four other Canadian cities, it appears that Vancouver and Edmonton would have the maximum and minimum energy savings respectively.

scholarly journals Comparative investigation of performance of gas dryer and two other types of domestic clothes dryers

2020 ◽  
Author(s):  
Xiao-Mei Huang ◽  
Lian-Sen Xiong ◽  
Yan-Wen Zheng ◽  
Hui-Qing Liu ◽  
Yi-Zhen Xu ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Ambient Temperature ◽  
Heat Pump ◽  
Thermal Energy ◽  
Dry Mass ◽  
Primary Energy ◽  
Comparative Investigation ◽  
Ambient Temperatures ◽  
Moisture Extraction

Abstract The moisture extraction rate (MER) and energy efficiency of domestic gas clothes dryers, heat-pump clothes dryers and electric clothes dryers were assessed. The assessment was performed with regard to five indices: the MER, specific MER, specific thermal energy consumption for dehumidification (mSPC), energy efficiency (ηt) and primary energy efficiency (η1). The effects of the dry mass of clothes (mBD) and the ambient temperature on the performance of the clothes dryers were evaluated. The experiments were divided into two parts. In the first part, the ambient temperature was 20°C, and mBD was set as 1.5, 2.5, 3.5, 4.5 and 6 kg. In the second part, mBD was 3.5 kg, and the performance of the dryers was tested at ambient temperatures of 5, 7.5, 10, 12.5, 15 and 20°C. The experimental results indicated that the gas dryer had the highest MER the heat-pump dryer had the best performance with regard to energy conservation and all three types of dryers had a higher MER and energy efficiency when the ambient temperature increased. The performance of the gas dryer was lower than that of heat-pump dryer when the temperature was 20°C. But when the temperature was < 9.5°C, the primary energy efficiency of the gas dryer was higher than that of the heat-pump dryer.

scholarly journals On the Performance of Night Ventilation in a Historic Office Building in Nordic Climate

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4159 ◽  
Author(s):  
Hossein Bakhtiari ◽  
Jan Akander ◽  
Mathias Cehlin ◽  
Abolfazl Hayati
Keyword(s):  
Thermal Comfort ◽  
Ambient Air ◽  
Ventilation Rate ◽  
Cold Climate ◽  
Office Building ◽  
Coefficient Of Performance ◽  
Thermal Mass ◽  
Electricity Use ◽  
Building Cooling ◽  
Night Ventilation

The effect of mechanical night ventilation on thermal comfort and electricity use for cooling of a typical historic office building in north-central Sweden was assessed. IDA-ICE simulation program was used to model the potential for improving thermal comfort and electricity savings by applying night ventilation cooling. Parametric study comprised different outdoor climates, flow rates, cooling machine’s coefficient of performance and ventilation units’ specific fan power values. Additionally, the effect of different door schemes (open or closed) on thermal comfort in offices was investigated. It was shown that night ventilation cannot meet the building’s total cooling demand and auxiliary active cooling is required, although the building is located in a cold climate. Night ventilation had the potential in decreasing the percentage of exceedance hours in offices by up to 33% and decreasing the total electricity use for cooling by up to 40%. More electricity is saved with higher night ventilation rates. There is, however, a maximum beneficial ventilation rate above which the increase in electricity use in fans outweighs the decrease in electricity use in cooling machine. It depends on thermal mass capacity of the building, cooling machine´s coefficient of performance, design ventilation rate, and available night ventilation cooling potential (ambient air temperature).

Solar-Assisted Heat Pump Drying of Coriander: An Experimental Investigation

2018 ◽  
Vol 26 (04) ◽  
pp. 1850037 ◽  
Author(s):  
Abbas Alishah ◽  
Mohammad Valizadeh Kiamahalleh ◽  
Fereshteh Yousefi ◽  
Anita Emami ◽  
Meisam Valizadeh Kiamahalleh
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Solar Collector ◽  
Coefficient Of Performance ◽  
Air Flow Rate ◽  
Drying Time ◽  
Air Temperatures ◽  
Moisture Extraction ◽  
Heat Pump Drying ◽  
Time And Energy

In this study, the solar-assisted heat pump dryer was designed, manufactured, tested and optimized for drying operations of coriander for its preservation. The heat of drying was mainly provided by a solar collector and a heat pump with two experimental modes of turned on and off. The air temperatures and velocity were identified as the critical drying variables. The responses of the experiments were evaluated in terms of coefficient of performance (COP), energy consumption and the specific moisture extraction rate (SMER). Dehumidification of coriander from the moisture contents of 0.9 to 0.1 kg/kg was considerable. The results demonstrated that utilizing heat pump noticeably decreases the drying time (down to [Formula: see text]25%), energy consumption (down to [Formula: see text]12%) and increases SMER (up to [Formula: see text]20%). The increasing of air flow rate and air temperature significantly led to decreasing the drying time and energy consumption, however, increasing the COP and SMER.

Rotary Compressor Performance at Low Ambient Temperatures

2020 ◽  
Vol 28 (04) ◽  
pp. 2050037
Author(s):  
S. Lowrey ◽  
G. Reboux
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Heat Pump ◽  
Simulated Data ◽  
Performance Testing ◽  
Rotary Compressor ◽  
Ambient Conditions ◽  
Ambient Temperatures ◽  
Compressor Performance ◽  
Performance Envelope

Small rotary compressors are used in domestic heat pump appliances, for example, in domestic dehumidifiers and heat pump clothes dryers. Compressor performance curves provided by the manufacturer can be based on testing at relatively high ambient temperatures, in some cases as high as 35∘C. This can be much higher compared with the ambient temperature in which the compressor operates when, for example, it is installed in a domestic dehumidifier which can operate in ambient temperatures as low as 10∘C. We have developed a compressor calorimeter to test a small R134a rotary compressor extracted from a commercial domestic dehumidifier and use this to measure compressor performance parameters including the isentropic and volumetric efficiencies and the compressor heat loss fraction. The performance testing has been carried out at ambient temperatures 10∘C, 15∘C, 20∘C and 25∘C for a fixed relative humidity of 70% to compare how the compressor performance varies with the ambient temperature, and to determine how well the compressor performs outside of the performance envelope provided by the manufacturer. The results show that isentropic and volumetric efficiency of these small compressors is relatively insensitive to variation in ambient temperature, even outside of the performance envelope provided by the manufacturer. However, the compressor heat loss fraction can, on average, double from 15% to 30%, between operation at ambient 25∘C and ambient 10∘C. The data obtained in this work is used to construct compressor sub-models for certain ambient temperatures. We show how these sub-models can be used to improve a domestic dehumidifier model for operation at low ambient conditions within the evaporator frosting regime and good agreement is obtained between experimental and simulated data. The authors are not aware of a domestic dehumidifier model designed to work at ambient temperatures within the frosting regime.

Performance Evaluation of an Air Source Heat Pump Coupled With a Building Integrated Photovoltaic/Thermal (BIPV/T) System

2014 ◽  
Author(s):  
Getu Hailu ◽  
Peter Dash ◽  
Alan S. Fung
Keyword(s):  
Performance Evaluation ◽  
Heat Pump ◽  
Ambient Air ◽  
Coefficient Of Performance ◽  
Air Source Heat Pump ◽  
Photovoltaic Arrays ◽  
Variable Capacity ◽  
Building Integrated Photovoltaic ◽  
Heating Mode ◽  
T System

A theoretical investigation of a variable capacity air-to-air air source heat pump (VC-ASHP) coupled with a building integrated photovoltaic/thermal (BIPV/T) system is presented in this paper. The BIPV/T system was integrated into the roof and the wall. Air was circulated behind the photovoltaic arrays to recover the thermal energy. The warm air recovered was supplied to the VC-ASHP. The thermal performance of the VC-ASHP was investigated for three scenarios when the heat pump is running in heating mode. The three scenarios are: (A) by feeding the ambient air to the ASHP; (B) by coupling the ASHP to the wall integrated BIPV/T only; and (C) by coupling the ASHP to the roof integrated BIPV/T only. The coefficient of performance (COP) of the VC-ASHP was evaluated for these three separate scenarios and compared. A typical winter day result suggests that the COP of the ASHP can be improved by coupling the VC-ASHP to either of the BIPV/T systems, i.e., either to the roof integrated BIPV/T system or to the wall integrated BIPV/T system.

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