scholarly journals The Influence of Internal Heat Exchanger on the Performance of Transcritical CO2 Water Source Heat Pump Water Heater

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1787
Author(s):  
Fan Feng ◽  
Ze Zhang ◽  
Xiufang Liu ◽  
Changhai Liu ◽  
Yu Hou
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Internal Heat ◽  
Water Source ◽  
Hot Water ◽  
Operational Performance ◽  
Water Heater ◽  
Source Temperature ◽  
Internal Heat Exchanger ◽  
Heat Pump Water Heater

The characteristics of the transcritical CO2 heat pump water heater (HPWH) system are; a lower inlet hot water temperature (Ti-hw) (sometimes this is lower than the water source temperature), and an outlet gas cooler temperature (To-gc) which is affected by the Ti-hw and often lower than the critical temperature. In order to study the effects of the internal heat exchanger (IHX) on the operational performance of the transcritical CO2 HPWH when To-gc is low, a transcritical CO2 water source HPWH experiment platform is established to conduct experimental research and comparative analysis on the operational performance of the transcritical CO2 water source HPWH, with or without IHX. It is found that, if only the coefficient of performance (COP) and heating at the optimal exhaust pressure of the transcritical CO2 water source HPWH were considered, COP and the heating of the non-IHX system would be slightly higher than those of the IHX system at the lower hot water flow and water source temperature, and this increase was not obvious. At the higher hot water flow rate and water source temperature, COP and the heating of the non-IHX system were also higher than those of the IHX system, and the increase was obvious. The experiment results showed that, near the optimal exhaust pressure, the variation range of COP and heating of the IHX system is relatively small, and the system has a relatively high stability.

scholarly journals Numerical study on the influence of internal heat exchanger in transcritical CO2 heat pumps under optimal pressure conditions

2021 ◽  
Vol 2116 (1) ◽  
pp. 012098
Author(s):  
F Illán-Gómez ◽  
J R García-Cascales ◽  
F J Sánchez-Velasco ◽  
V Sena-Cuevas ◽  
R Otón-Martínez
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Strong Influence ◽  
Numerical Study ◽  
Internal Heat ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Water Heater ◽  
Internal Heat Exchanger ◽  
Heat Pump Water Heater

Abstract This paper presents a numerical study on the influence of internal heat exchanger (IHX) exchanging surface in the performance of a transcritical CO2 heat pump water heater at different operating conditions. Five different IHX geometries and four different evaporation temperatures have been studied with water temperature ranging from 10 °C to 60 °C at the gas cooler inlet. The results show a strong influence of IHX characteristics on system’s performance.

Energy Consumption Modeling of a Heat Pump System for Combined Space Conditioning and Residential Water Heating in a Typical Household in Quito, Ecuador

2016 ◽  
Author(s):  
Gabriel Agila ◽  
Guillermo Soriano
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Thermal Storage ◽  
Hot Water ◽  
Water Heating ◽  
Water Heater ◽  
Pump System ◽  
Detailed Model ◽  
Heat Pump Water Heater ◽  
Residential Water

This research develops a detailed model for a Water to Water Heat Pump Water Heater (HPWH), operating for heating and cooling simultaneously, using two water storage tanks as thermal deposits. The primary function of the system is to produce useful heat for domestic hot water services according to the thermal requirements for an average household (two adults and one child) in the city of Quito, Ecuador. The purpose of the project is to analyze the technical and economic feasibility of implementing thermal storage and heat pump technology to provide efficient thermal services and reduce energy consumption; as well as environmental impacts associated with conventional systems for residential water heating. An energy simulation using TRNSYS 17 is carried to evaluate model operation for one year. The purpose of the simulation is to assess and quantifies the performance, energy consumption and potential savings of integrating heat pump systems with thermal energy storage technology, as well as determines the main parameter affecting the efficiency of the system. Finally, a comparative analysis based on annual energy consumption for different ways to produce hot water is conducted. Five alternatives were examined: (1) electric storage water heater; (2) gas fired water heater; (3) solar water heater; (4) air source heat pump water heater; and (5) a heat pump water heater integrated with thermal storage.

Theoretical investigation on the heating performance of a recuperative heat pump water heater using CO2/HCs with large temperature glides in cold regions

2021 ◽  
pp. 1-22
Author(s):  
Jielin Luo ◽  
Qin Wang ◽  
Zhen Zhao ◽  
Kaiyin Yang ◽  
Guangming Chen ◽  
...  
Keyword(s):  
Heat Pump ◽  
Temperature Difference ◽  
Hot Water ◽  
Large Temperature ◽  
Water Heater ◽  
Ambient Temperatures ◽  
Heating Performance ◽  
Heat Pump Water Heater ◽  
Vapor Injection ◽  
Injection Cycle

Abstract Considering the issues of environmental pollution and energy efficiency, heat pumps are gradually replacing traditional coal combustion for heating at low ambient temperatures. In this paper, eco-friendly CO2/HCs with large temperature glides are applied in a single-stage recuperative heat pump water heater. Its heating performance is theoretically investigated under the working condition of producing circulating hot water in typical winter of northern China, with medium temperature difference between supply/return water and large temperature difference between air inlet and water inlet. Due to its simple structure, low initial investment and high efficiency, its potential for producing circulating hot water is demonstrated. Exergy analyses are conducted to reveal the significant influence of the exergy losses of heat exchanger on system performance. For specified CO2/HC, optimal COP is obtained through global optimization of cycle pressures and mixture concentration. The heating performances of different CO2/HCs are compared, among which CO2/R600 and CO2/R600a behave better. Meanwhile, a typical vapor-injection cycle is used to demonstrate priorities on the heating performance of this recuperative cycle, in which the COP of recuperative cycle using CO2/R600 is more than 3.4% higher than that of the vapor-injection cycle. The results obtained in this paper provide a simple and efficient solution for producing circulating hot water at low ambient temperatures.

scholarly journals A Compact and Fast Temperature-Response Heat Pump Water Heater

1997 ◽  
Author(s):  
B. J. Huang ◽  
F. H. Lin
Keyword(s):  
Heat Pump ◽  
Water Discharge ◽  
Temperature Response ◽  
Control Device ◽  
Hot Water ◽  
Water Heater ◽  
Supply Tank ◽  
Heat Pump Water Heater ◽  
Temperature Recovery ◽  
Line Switching

A compact and fast temperature-response heat pump water heater was designed using multiple tanks and a sequential control device. The supply tank was heated as a priority by a freon-line switching device to increase the temperature recovery speed. A dual-tank prototype with 100-liter capacity was built and tested. The experimental results show that the time for temperature recovery of the supply tank from 42°C to 54°C reaches 10–20 minutes and COP reaches 2.0–3.0 during various seasons. The prototype tests show that an energy saving around 50%–70% as compared to the electrical water heater can be obtained. The hot water discharge efficiency of the heat pump is 0.912.

Performance of Add-On Heat Pump Water Heater (HPWH) Systems and Their Impacts on Electric Utility Loads

2010 ◽  
Author(s):  
Yahya I. Sharaf-Eldeen ◽  
Craig V. Muccio ◽  
Eric Gay
Keyword(s):  
Heat Pump ◽  
Energy Savings ◽  
Electric Energy ◽  
Electric Heating ◽  
Electric Utility ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Energy Output ◽  
Water Heater ◽  
Heat Pump Water Heater

This work involves measurements, analyses, and evaluations of the performance of add-on, Heat Pump Water Heater (HPWH) systems in residential and small commercial applications. Two air-source Heat Pump (HP) systems rated at 7,000- and 12,000-BTU (2.051- and 3.517-kWh), were utilized in this work. The two HPs were retrofitted to two 50-gallon (189.3 liters) electric-resistance storage water-heaters with their electric heating elements removed. A third, standard electric water-heater (EWH), was used for comparison. The testing set-up was fully instrumented for measurements of pertinent parameters, including inlet and outlet water temperatures, inlet and outlet air temperatures of the HPs, temperature and humidity of the air in the surrounding space, volume of water draws out of the storage heater tanks, as well as electric energy consumptions of the systems. Several performance measures were used in this work, including the Coefficient of Performance (COP), which is a measure of the instantaneous energy output in comparison with the energy input; Energy Factor (EF), which is an average measure of the COP taken over extended periods of time; and the First Hour Rating (FHR), which is a measure of the maximum volume of hot water that a storage type water-heater can supply to a residence within an hour. The results obtained clearly indicate that, HPWH systems are much more efficient as compared to standard EWHs. While the average value of the EF for a standard EWH is close to 1.0, the HPWH systems yield EFs averaging more than 2.00, resulting in annual energy savings averaging more than 50%. The results also showed that, HPWH systems are effective at reducing utility peak demand-loads, in addition to providing substantial cost savings to consumers.

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