A Study on the Performance of a Cascade Heat Pump for Generating Hot Water

The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.

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An Analytical Comparison Between the Performance of a Hot Water Heat Pump With a Non-Azeotropic Refrigerant Mixture and a Pure Refrigerant

ASME 1997 Turbo Asia Conference ◽

10.1115/97-aa-042 ◽

1997 ◽

Cited By ~ 1

Author(s):

F. J. Smit ◽

Josua P. Meyer

Keyword(s):

Heat Pump ◽

Boiling Point ◽

Fossil Fuels ◽

Pressure Ratio ◽

Heat Pumps ◽

Hot Water ◽

Coefficient Of Performance ◽

Refrigerant Mixture ◽

Compressor Pressure Ratio ◽

Heating Capacity

The applications of hot water in the industrial, domestic and mining applications are numerous, and these are only a few of the core areas of use. In these applications fossil fuels and electrical resistance systems are usually used to heat water to temperatures near boiling point. The refrigerant R22, that is currently being used in hot water heat pumps, delivers hot water temperatures from 60 °C to 65 °C. This limits the applications of hot water heat pumps. This analytical study uses three comparison methods to investigate and compare the potential of a non-azeotropic refrigerant mixture consisting of R22 and R142b. From the results different advantages of non-azeotropic refrigerant mixtures are evident. Depending on the application, if the results of a non-azeotropic refrigerant mixture are compared with a pure R22 heat pump, an increase in hot water temperatures to above boiling point, an increase in coefficient of performance, an increase in capacity and a decrease in compressor pressure ratio are possible. Unfortunately, not all these advantages are valid for each application. For instance, extremely high hot water temperatures are obtained, whilst the heating capacity is excessively low.

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Factors Shaping A/W Heat Pumps CO₂ Emissions—Evidence from Poland

Energies ◽

10.3390/en14061576 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1576

Author(s):

Piotr Jadwiszczak ◽

Jakub Jurasz ◽

Bartosz Kaźmierczak ◽

Elżbieta Niemierka ◽

Wandong Zheng

Keyword(s):

Air Quality ◽

Power System ◽

Heat Pump ◽

Heat Pumps ◽

Hot Water ◽

Coefficient Of Performance ◽

Conventional Heating ◽

Additional Stress ◽

The European Union ◽

Energy Mix

Heating and cooling sectors contribute to approximately 50% of energy consumption in the European Union. Considering the fact that heating is mostly based on fossil fuels, it is then evident that its decarbonization is one of the crucial tasks for achieving climate change prevention goals. At the same time, electricity sectors across the globe are undergoing a rapid transformation in order to accommodate the growing capacities of non-dispatchable solar and wind generators. One of the proposed solutions to achieve heating sector decarbonization and non-dispatchable generators power system integration is sector coupling, where heat pumps are perceived as a perfect fit. Air source heat pumps enable a rapid improvement in local air quality by replacing conventional heating sources, but at the same time, they put additional stress on the power system. The emissions associated with heat pump operation are a combination of power system energy mix, weather conditions and heat pump technology. Taking the above into consideration, this paper presents an approach to estimate which of the mentioned factors has the highest impact on heat pump emissions. Due to low air quality during the heating season, undergoing a power system transformation (with a relatively low share of renewables) in a case study located in Poland is considered. The results of the conducted analysis revealed that for a scenario where an air-to-water (A/W) heat pump is supposed to cover space and domestic hot water load, its CO2 emissions are shaped by country-specific energy mix (55.2%), heat pump technology (coefficient of performance) (33.9%) and, to a lesser extent, by changing climate (10.9%). The outcome of this paper can be used by policy makers in designing decarbonization strategies and funding distribution.

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Experimental Study of Heating-Cooling Combined Ground Source Heat Pump System with Horizontal Ground Heat Exchanger

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.374-377.398 ◽

2011 ◽

Vol 374-377 ◽

pp. 398-404 ◽

Cited By ~ 1

Author(s):

Ying Ning Hu ◽

Ban Jun Peng ◽

Shan Shan Hu ◽

Jun Lin

Keyword(s):

Heat Exchanger ◽

Heat Exchange ◽

Heat Pump ◽

Hot Water ◽

Coefficient Of Performance ◽

Ground Heat Exchanger ◽

Pipe Length ◽

Pump System ◽

Heat Pump System ◽

Heating And Cooling

A hot-water and air-conditioning (HWAC) combined ground sourse heat pump(GSHP) system with horizontal ground heat exchanger self-designed and actualized was presented in this paper. The heat transfer performance for the heat exchanger of two different pipe arrangements, three layers and four layers, respectively, was compared. It showed that the heat exchange quantity per pipe length for the pipe arrangement of three layers and four layers are 18.0 W/m and 15.0 W/m. The coefficient of performance (COP) of unit and system could remain 4.8 and 4.2 as GSHP system for heating water, and the COP of heating and cooling combination are up to 8.5 and 7.5, respectively. The power consumption of hot-water in a whole year is 9.0 kwh/t. The economy and feasibility analysis on vertical and horizontal ground heat exchanger were made, which showed that the investment cost per heat exchange quantity of horizontal ground heat exchanger is 51.4% lower than that of the vertical ground heat exchanger, but the occupied area of the former is 7 times larger than the latter's.

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

Energies ◽

10.3390/en12030479 ◽

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.

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Heat Pumps for Energy Saving of Building Hot Water Supply

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.347-353.587 ◽

2011 ◽

Vol 347-353 ◽

pp. 587-590

Author(s):

Qing Hai Luo ◽

Zheng Zuo

Keyword(s):

Energy Efficiency ◽

Energy Consumption ◽

Water Supply ◽

Energy Saving ◽

Heat Pump ◽

Heat Pumps ◽

Hot Water ◽

Low Energy ◽

Water Heaters ◽

Hot Water Supply

This paper analyzes the energy consumption of hot water supply in buildings and the insurmountable shortcoming of low energy efficiency of conventional water heaters, and investigates the progress and problems of developing heat pump water heaters. It is pointed out that developing of heat pump water heaters is one of the efficient approaches to improve the energy efficiency of hot water supply.

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Analysis of an Integrated Thermal Energy System for Applications in Cold Regions

Journal of Energy Resources Technology ◽

10.1115/1.4050887 ◽

2021 ◽

pp. 1-32

Author(s):

Bismark Addo-Binney ◽

Wahid Besada ◽

Martin Agelin-Chaab

Keyword(s):

Heat Pump ◽

Pump Energy ◽

Energy System ◽

Heat Pumps ◽

Environmental Data ◽

Coefficient Of Performance ◽

Space Heating ◽

Cold Regions ◽

Heating Capacity ◽

Better Than

Abstract This paper performed analyses on a proposed direct wind-powered heat pump integrated with a pond which serves as an evaporator for space heating in cold regions. The analysis was conducted using environmental data for selected locations in Canada and the Engineering Equation Solver. Three different pairings of heat pumps and wind turbines were studied (a wind-powered heat pump with a pond as an evaporator, a wind-powered heat pump without a pond, and an electricity-powered heat pump). Energy and exergy analyses were performed on the systems. The novelty in the present study is in the use of a wind turbine to directly power the heat pump and using a pond as the evaporator. The results show that the proposed system has the highest coefficient of performance compared to the others. The average coefficient of performance for the selected locations is 2.7, which is at least 67% better than the others. Similarly, the overall exergy for the proposed system is 16.9%, which is at least 40% better than the others. The average heating capacity of the selected locations for the proposed system is 4.5 kW, which is from 29% to 300% better than the others. Additionally, the sustainability index for the proposed system is the highest for the proposed system. The results have shown that the proposed system has superior overall performance for space heating in cold regions.

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Practical study on heat pump enhancement by the solar energy

E3S Web of Conferences ◽

10.1051/e3sconf/202128801069 ◽

2021 ◽

Vol 288 ◽

pp. 01069

Author(s):

Omar Abdulhadi Mustafa Almohammed ◽

Farida Mizkhatovna Philippova ◽

Fouad Ibrahim Alhajj Hassan ◽

Nail Farilovich Timerbaev ◽

Anatoliy Anatolyevich Fomin

Keyword(s):

Heat Exchanger ◽

Solar Energy ◽

Heat Pump ◽

Technical College ◽

Heat Pumps ◽

Coefficient Of Performance ◽

Laboratory Model ◽

Additional Heat ◽

Heating And Cooling ◽

Positive Effect

The heat pumps system is one of the most remarkable system that is widely used around the world, their capacity is different according to necessity. The energy consumption in those systems will limit their effectiveness. This study will try to prove the positive reactance of the new changes (the additional heat exchanger) on the heat pump work, where the power consumption will reduce about (13-17%). The study includes the experimental results of the laboratory model, which has been manufactured in the laboratories of the technical college of Mosul/Northern technical university-Iraq. The model consists of the heat pump that was improved by using the additional heat exchanger, its duty is to heat the refrigerant before entering the compressor, by using solar energy. The results of this work prove the positive effect of the additional heat exchanger, on the coefficient of performance of the heat pump, in both modes of heating and cooling. The conclusions are useful to the industries that deal with heat pumps.

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Experimental Research on Performance of Heat Pump Using Shower Waste Water as Heat Source

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.480-481.887 ◽

2011 ◽

Vol 480-481 ◽

pp. 887-892 ◽

Cited By ~ 1

Author(s):

Han Dong Wang

Keyword(s):

Waste Water ◽

Energy Saving ◽

Heat Pump ◽

High Energy ◽

Hot Water ◽

Coefficient Of Performance ◽

Small Scale ◽

Stable Operation ◽

Water Tank ◽

Water Heater

As we know, there is plenty of waste hot water produced by families’ shower or Sauna and drained directly into the environment. It causes high energy consumption and heat pollution to the environment. In order to recover the heat of shower waste water to save energy, we developed a small scale shower waste water source heat pump (SWWHP) water heater and carried out experiments on it to study its heating performance. Experiments showed that this heat pump water heater system had advantages such as quick starting, compact structure, no need of hot water tank, stable operation and energy saving, etc. It could be used to supply hot water above 40°C for shower or heating, ventilation and air conditioning (HVAC). Measured data showed that during the whole year, when the temperatures of waste water and city water were 20.1～35°C, 20.1～30°C, respectively, it could supply hot water at volumetric flow rate of 2.5～9.6L/min and temperature of 40.1～51.2°C and its heating coefficient of performance (COPh) varied in the range of 3.06～4.81. It could supply enough shower hot water in the whole year in South China and the energy saving efficiency was obvious. Analysis also showed that the COPh was closely relevant to the ratio of temperature differences of waste water and hot water, i.e., ΔTw/ΔTh. The correlation equation of COPh and ΔTw/ΔTh was obtained by method of data regression and it could be used to evaluate the performance of the SWWHP water heater system with error of ±6%.

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Impact of Compressor Drive System Efficiency on Air Source Heat Pump Performance for Heating Hot Water

Sustainability ◽

10.3390/su122410521 ◽

2020 ◽

Vol 12 (24) ◽

pp. 10521

Author(s):

Mariusz Szreder ◽

Marek Miara

Keyword(s):

Heat Pump ◽

Air Temperature ◽

Heating System ◽

Operating Conditions ◽

Drive System ◽

Hot Water ◽

Coefficient Of Performance ◽

Air Source Heat Pump ◽

Heating Capacity ◽

The Impact

A standard Polish household with a central heating system powered by a solid fuel furnace was chosen as a case study. The modular Air Source Heat Pump (ASHP) was used to heat the hot water outside the heating season. In this article comparative studies of the impact of the compressor drive system used on the energy efficiency of the heat pump have been carried out in operating conditions. The ASHP heating capacity and coefficient of performance (COP) were determined for the outside air temperature in the range from 7 to 22 °C by heating the water in the tank to a temperature above 50 °C. For the case of a fixed speed compressor, average heating capacity in the range 2.7−3.1 kW and COP values in the range 3.2−4.6 depending on the evaporator supply air temperature were obtained. Similarly, for the inverter compressor, the average heating capacity in the range of 2.7−5.1 kW was obtained for the frequency in the range of 30–90 Hz and COP in the range 4.2−5.7, respectively. On cool days, the average heating capacity of the heat pump decreases by 12%. For the simultaneous operation of two compressors with comparable heating capacity, lower COP values were obtained by 20%.

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