Design and Experimental Research of Gas Cooler for CO2 Heat Pump Water Heater

2010 ◽  
Vol 156-157 ◽  
pp. 1161-1164
Author(s):  
Ye Feng Liu ◽  
Guo Dong Gong ◽  
Xi Chen
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Hot Water ◽  
Global Environment ◽  
Heat Transfer Characteristics ◽  
Water Heater ◽  
Working Pressure ◽  
Heat Pump Water Heater ◽  
Double Pipe ◽  
Pipe Heat

The advantages of CO2 Heat Pump water heater include: CO2 is one of natural refrigerants and does not affect the global environment as many other HFCs refrigerants; CO2 heat pump water heater can produce hot water up to 90 ,which is higher than HFCs heat pump water heater(about 55 ).So the application of CO2 Heat Pump water heater is potential. But the Working pressure of CO2 Heat Pump Water Heater is about 9~12Mpa and is 3-5times of HFCs heat pump water heater’. Gas cooler is one of important part for CO2 heat pump water heater, and it must meet the needs of not only pressurization but also heat transfer. So it is important to design gas cooler correctly. In the paper, one system of CO2 Trans-critical Cycle Heat Pump Water Heater is designed, and double-pipe gas cooler is designed The heat transfer characteristics of CO2 in gas cooler with water in double-pipe heat exchanger was experimentally investigated. Experimental results showed that the gas cooler can meet the need of trans-critical CO2 cycle heat pump water heater. All the work is valuable for the application of CO2 heat pump water heater.

scholarly journals EXPERIMENTAL STUDY OF HEAT TRANFER AUGMENTATION USING AIR BUBBLE INJECTION AND (Al2O3 /WATER) NANOFLUID FLOW IN DOUBLE PIPE HEAT EXCHANGERS

2021 ◽  
Vol 21 (2) ◽  
pp. 96-117
Author(s):  
Dhirgham A. Alkhafaji ◽  
Hameed K. Hamzah ◽  
Haider S. Hadi
Keyword(s):  
Heat Transfer ◽  
Cold Water ◽  
Volume Flow ◽  
Hot Water ◽  
Air Bubbles ◽  
Heat Transfer Characteristics ◽  
Flow Rates ◽  
Air Bubble ◽  
Double Pipe ◽  
Pipe Heat

In the present work, an experimental study on how to increase the heat transfer coefficient (HTC) in double pipe heat exchanger (DPHE) use of a variety of Al2O3 Nano-dispersion concentrations mixed in water as base fluid with air bubble injection for counter flow arrangement under turbulent flow conditions with (Re) Reynold number range from (6000 t0 45000) . The thermal performance of (DPHE) has been enhanced with the use of two techniques. The first, is represented by adding nanoparticles to hot water (inner pipe) raising the (HTC) inside the inner tube. Increase the volume concentration cause increase in the viscosity of the nanofluid leading to increase in friction factor .Secondly is represented by Air bubble injection in outer pipe with cold water to enhance the (HTC). The mobility of air bubbles inside the water from down to up by the force of the buoyancy, and the movement of these air bubbles results in significant mixture and turbulence within the water. The variations of number of thermal units (NTU), exergy loss, dimensionless exergy and (Nu) are evaluated. The investigated parameters were cold water volume flow rates (8, 10, 12 and14) l/min, flow in outer tube. Also, three different volume flow rates of air (12, 16 and 20) l/min mixed with water in outer tube. The volume flow rates of hot water remains constant at (8 l/min) flow in inner pipe with three volumetric concentrations of given nanofluid. The results showed that the air bubble injection throughout the tube gave maximum enhancement in heat transfer characteristics followed by the no air bubble injection. Since the enhancement in heat transfer characteristics varies linearly with the volumetric concentration of Nanofluids, Nanofluids with 0.3% of Al2O3 nanoparticles gave more enhancements in (HTC) than the case without nanofluid. The Nusselt number increased about (8% - 45%).  

Experimental Study on Gas Cooler Heat Transfer Characteristics Applied in CO2 Supercritical Cycle Heat Pump Water Heater

2010 ◽  
Author(s):  
Yefeng Liu ◽  
Hua Zhang ◽  
Caoping Cai ◽  
Weidong Wu ◽  
Yingxia Qi
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Water Flow Rate ◽  
Water Flux ◽  
Cooling Water ◽  
Outlet Temperature ◽  
Heat Transfer Characteristics ◽  
Water Heater ◽  
Transfer Characteristics ◽  
Heat Pump Water Heater

One CO2 heat pump water heater test apparatus was built in the paper. The heat transfer characteristics of CO2 in gas cooler with water in double-pipe heat exchanger was experimentally investigated. The effects of variation of cooling water flux on heat transfer characteristics, outlet temperature of water, COP and CO2 temperature were analyzed. The influences of cooling water flux to heat exchange about CO2 side, water side, and the CO2 and water temperature matching was analyzed. Experimental results showed that the supercritical CO2 heat pump water heater can acquire higher temperature of outlet water up to 80°C than those conventional Freon heat pump water heater, and the COP of the system increased with the increase of water flow rate through gas cooler. All the work was valuable for the application of CO2 heat pump water heater.

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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