Performance Study of Structure Improvement Design for Storage-Type Domestic Electrical Water-Heaters Based on the CFD Simulation

2010 ◽  
Vol 129-131 ◽  
pp. 602-606
Author(s):  
Zhi Jun Zhang ◽  
Shi Wei Zhang ◽  
Cheng Hai Xu
Keyword(s):  
Cfd Simulation ◽  
Discharge Rate ◽  
Hot Water ◽  
Dynamics Simulation ◽  
Water Tank ◽  
Performance Study ◽  
Water Heater ◽  
Water Heaters ◽  
Traditional Structure ◽  
Structure Improvement

The 3D physical model with two different structure of the electrical water heater was built. The performance of water heater was studied by computer fluid dynamics simulation (CFD). The heater performance is characterized the discharge efficiency, extraction efficiency and fraction of heat recoverable. It was 73.7%, 45% and 49.8% respectively with conventional structure, and it was 81.1%, 54.1% and 59.6% respectively of improved structure with discharge rate was 5L/min when all initial hot water temperature was 90°C. The temperature distribution of different discharged stage was also disclosure. The water inner the water tank of improved structure has the better thermal stratification than traditional structure. It was also agreed with the water heat performance.

Performance Study for Storage-Type Domestic Electrical Water-Heaters with Double Tank Based on the CFD Simulation

2010 ◽  
Vol 29-32 ◽  
pp. 1701-1705
Author(s):  
De Xi Wang ◽  
Zhi Jun Zhang
Keyword(s):  
Cfd Simulation ◽  
Discharge Rate ◽  
Hot Water ◽  
Dynamics Simulation ◽  
Water Tank ◽  
Performance Study ◽  
Water Heater ◽  
Water Heaters ◽  
Computer Fluid Dynamics ◽  
The Mathematical Model

The 3D physical model of the electrical water heater was built. The mathematical model of hot flow was resolved by computer fluid dynamics simulation (CFD). The effects of the rate of water draw on the heater performance have been investigated. The heater performance is characterized the discharge efficiency, extraction efficiency and fraction of heat recoverable. It was 85.9%, 66.0% and 70.9% respectively, and it was 74.0%, 27.3% and 39.9% respectively with discharge rate was 10L/min when all initial hot water temperature was 70°C. The water inner the water tank of draw rate 5L/min was well thermal stratification. It was also expatiated by the distribution temperature of CFD simulation.

A New Performance Estimate Method for Design of Storage-Type Domestic Electrical Water-Heaters Based on the CFD Simulation

2010 ◽  
Vol 129-131 ◽  
pp. 463-466
Author(s):  
Li Li Zhao ◽  
Zhi Jun Zhang ◽  
Shi Wei Zhang
Keyword(s):  
Water Temperature ◽  
Cfd Simulation ◽  
Cold Water ◽  
Discharge Rate ◽  
Water Discharge ◽  
Hot Water ◽  
New Method ◽  
Dynamics Simulation ◽  
Water Heater ◽  
Water Heaters

The 3D physical model of the electrical water heater was built. The water-heater performance was resolved by computer fluid dynamics simulation (CFD). The heater performance is characterized by a new method rather than that the discharge efficiency, extraction efficiency and fraction of heat recoverable. The new method is based on the constant discharge water temperature and rate for end user, 5L/min and 43°C that include the hot water from EWH and cold water from outside EWH. But the water discharge rate from EWH was variable as the water temperature discharge from EWH was variable. Compared with the traditional method, it is more close to the user using reality condition.

Performance Estimate for Design of Storage-Type Domestic Electrical Water-Heaters Based on the CFD Simulation

2010 ◽  
Vol 26-28 ◽  
pp. 732-735
Author(s):  
Zhi Jun Zhang ◽  
Shi Wei Zhang ◽  
Cheng Hai Xu
Keyword(s):  
Water Temperature ◽  
Cfd Simulation ◽  
Cold Water ◽  
Discharge Rate ◽  
Water Discharge ◽  
Hot Water ◽  
New Method ◽  
Dynamics Simulation ◽  
Water Heater ◽  
Discharge Efficiency

The 3D physical model of the electrical water heater was built. The water-heater performance of two kind structures was resolved by computer fluid dynamics simulation (CFD). The heater performance is characterized by a new method rather than that the discharge efficiency, extraction efficiency and fraction of heat recoverable. The new method is based on the constant discharge water temperature and rate for end user, 5L/min and 43°C that include the hot water from EWH and cold water from outside EWH. But the water discharge rate from EWH was variable as the water temperature discharge from EWH was variable. The discharge efficiency of conventional EWH was 79.312%, and the discharge efficiency of improved EWH was 84.97%. Compared with the traditional method, it is more close to the user using reality condition.

Performance Study of Storage-Type Domestic Electrical Water-Heaters with Wedged Inlet: Unsteady Water Discharge Rate

2010 ◽  
Vol 44-47 ◽  
pp. 299-303
Author(s):  
Zhi Jun Zhang ◽  
Shi Wei Zhang ◽  
Cheng Hai Xu
Keyword(s):  
Temperature Profile ◽  
Discharge Rate ◽  
Water Discharge ◽  
Dynamics Simulation ◽  
Performance Study ◽  
Water Heaters ◽  
Computer Fluid Dynamics ◽  
Unsteady Discharge ◽  
Discharge Efficiency ◽  
Storage Type

The unsteady water discharge rate on performance of storage-type domestic electrical water-heaters with wedged inlet was studied by computer fluid dynamics simulation (CFD). The results were compared with those of conventional design EWHs having the same tank size. The heater performance is characterized the discharge efficiency, extraction efficiency and fraction of heat recoverable. The water draw-off temperature profile of steady and unsteady water discharge rate has nothing difference for wedged inlet structure, both curve was overlapped. The almost the same energy utility efficiency was gotten both steady and unsteady discharge rate for wedged inlet structure. The obviously difference of water draw-off temperature profile was shown for conventional inlet structure. Water draw-off temperature profile of unsteady discharge rate was decreased faster than steady discharge rate. The energy utility efficiency of unsteady discharge rate was also lower than steady discharge rate. The results were shown that the wedged inlet structure heater has excellent performance for energy utility efficiency under unsteady discharge rate.

CFD Solution and Experimental Testing of Buoyancy-Driven Convection Caused by Condensers Immersed in a Water Tank of HPWH

2003 ◽  
Author(s):  
Zhiming Gao ◽  
Viung C. Mei ◽  
Fang C. Chen
Keyword(s):  
Water Temperature ◽  
Heat Pump ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Electricity Consumption ◽  
Water Tank ◽  
Water Heater ◽  
Water Heaters ◽  
C 30 ◽  
Tube Condenser

Heat pump water heaters can cut electricity consumption, comparing with the conventional electric resistant water heating tanks by half. A conventional heat pump water heater (HPWH) requires a water circulating pump to sample water temperature every 15 minutes in the tank and to draw water to a condenser-water heat exchanger outside the tank, if water temperature is below the set point. The pump would be on at least once every 15 minutes, 24 hours a day. The novel design presented in this study was to insert the condenser coil through the opening on the top of the water tank. This design eliminated the need of the water circulating pumps, and thus greatly improved the reliability of the HPWH systems. Two types of condenser coil designs were considered; one was a bayonet tube (tube-in-tube) and one was the “U” tube. Previous test data indicated that “U” tube design performed better than the bayonet tube condenser coil, and thus only “U” tube condenser coil was considered in the study. With straight “U” tubes inserted into the tank, it was found that the convective heat transfer was not strong enough to break water temperature stratification in the tank, which resulted in a temperature differential of 16°C (30°F) from top to bottom. However, when the coil was built in “L” shape, the water stratification disappeared. A computational fluid dynamics code, CFD, was used to study the straight and L shaped condenser coils. Results from CFD simulation were compared with the experimental data and found they were close to each other.

scholarly journals Assessment and Modeling of Household-Scale Solar Water Heater Application in Zambia: Technical, Environmental, and Energy Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Mehdi Jahangiri ◽  
Esther T. Akinlabi ◽  
Sam M. Sichilalu
Keyword(s):  
Fossil Fuels ◽  
Hot Water ◽  
Climate Data ◽  
Ghg Emission ◽  
Water Heater ◽  
Ghg Mitigation ◽  
Solar Water ◽  
Water Heaters ◽  
Industrial Sectors ◽  
Solar Water Heaters

Solar water heaters (SWHs) are one of the most effective plans for general and easy use of solar energy to supply hot water in domestic and industrial sectors. This paper gives the first-ever attempts to assess the optimal localization of SWHs across 22 major cities in Zambia, as well as determine the possibility of hot water generation and model the greenhouse gas (GHG) emission saving. The climate data used is extracted by using the MeteoSyn software which is modeled in TSOL™. Results show the high potential of GHG emission reduction due to nonconsumption of fossil fuels owing to the deployment of SWHs, and three cities Kabwe, Chipata, and Mbala had the highest GHG mitigation by 1552.97 kg/y, 1394.8 kg/y, and 1321.39 kg/y, respectively. On average, SWHs provide 62.47% of space heating and 96.05% of the sanitary hot water requirement of consumers. The findings have shown the potential for the deployment of SWHs in Zambia. The techno-enviro study in this paper can be used by the policymakers of Zambia and countries with similar climates.

Evaluation of Passive Anti-Fouling Technology Applied to CO2 Heat Pump Water Heaters

2014 ◽  
Author(s):  
Portia Murray ◽  
Stephen J. Harrison ◽  
Ben Stinson
Keyword(s):  
Heat Transfer ◽  
Water Supply ◽  
Heat Pump ◽  
Hot Water ◽  
Normal Operation ◽  
Mineral Deposits ◽  
Reverse Direction ◽  
Water Tank ◽  
Flow Rates ◽  
Water Heaters

Heat pump water heaters are increasing in popularity due to their increased energy efficiency and low environmental impact. This paper describes the experimental testing of a transcritical CO2 heat pump water heater at Queen’s University. A modified 4.5 kW Eco-Cute unit was studied. It sourced heat from a constant temperature water supply and rejected the heat to a 273 litre hot water tank through a gas-cooler. The high temperatures that occur in the gas-cooler of this unit make it ideally suited for natural convection, (i.e., thermosyphon) circulation on the potable water side. This has the potential to reduce pumping power, simplify system operation and design, and increase thermal stratification in the hot water storage tank. This configuration, however, is susceptible to the accumulation of sediments, scale and mineral deposits (i.e., fouling) in geographic regions where high mineral deposits may be present in the water supply. To counteract fouling in these cases, a passive back-flushing system was proposed to prevent the accumulation of deposits on the heat transfer surfaces of the gas-cooler. As hot water is drawn from the system, the cold “mains” supply water is directed through the gas-cooler in the reverse direction of normal operation, scouring the heat transfer surfaces and dissolving deposits of inverse-soluble salts which are a major contributor to fouling on hot heat transfer surfaces. The gas-cooler used was a specially designed unit that, although offering high performance in a compact unit, may be susceptible to the fouling and blockage of the heat transfer passages when used at thermosyphon flow rates. Experiments were conducted to evaluate the effects of the back-flush operation on heat pump performance (i.e., COP) and operation. These were conducted under controlled laboratory conditions, at a range of draw flow rates and temperatures, and are summarized in this paper.

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.

Solar Water Heaters: A Review of Systems Research and Design Innovation

Green ◽  
2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Brian Norton
Keyword(s):  
System Development ◽  
Unit Cost ◽  
Hot Water ◽  
Water Heating ◽  
Water Heater ◽  
Solar Water Heating ◽  
Solar Water ◽  
Water Heaters ◽  
Systems Research ◽  
And Performance

AbstractSolar water heating can be considered to be an established mature technology. The achievement of this status is the outcome of over a century of system development that culminated with a flourish of innovation in the last thirty years. Drivers for research and development have been achieving economic viability by devising systems that, for specific applications in particular climate contexts produced more hot water per unit cost. Reductions in both initial capital and installation costs have been achieved as well as in those associated with subsequent operation and maintenance. Research on solar water heating is discussed with the emphasis on overall systems though some key aspects of component development are also outlined. A comprehensive taxonomy is presented of the generic types of solar water heater that have emerged and their features, characteristics and performance are discussed.

The Device of the Automatic Backflow in Solar Water Heater-Temperature Control and Backflow for Pipe of Water Heater

2013 ◽  
Vol 827 ◽  
pp. 99-104
Author(s):  
Bin Li ◽  
Xi Chen ◽  
Xin Hao Li ◽  
Lu Kuan Ma ◽  
Wen Bo Lu ◽  
...  
Keyword(s):  
Water Resources ◽  
Cold Water ◽  
Hot Water ◽  
Water Tank ◽  
Solar Water Heater ◽  
Recycle Water ◽  
Delay Effect ◽  
Water Heater ◽  
Domestic Water ◽  
Solar Water

Now in general use in solar water heater, there is a long pipeline between water heater and tap, we have to empty the stored cold water before we use the hot water; and usually the water cannot meet required temperature due to the heating delay effect, thus the water also should be emptied, which leads to a waste of water resources. In order to solve this water wastage, we propose a device which can help to control the temperature and backflow of the water in water heater. The device accomplishes backflow of cold water automatically under the effect of gravity, and refluxed water will be stored in the recycle-water tank, thus ensuring the result that the water temperature satisfies the requirement. After the recycle-water tank is full, it will trigger the buoy to control the relay switch, then the water pump start to work to force the water into the water heater tank. Thus, realizing the recycling of water. This device can significantly save water resources in domestic water, and it has a broad market prospect.

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