A Coefficient to Characterize Mixing in Solar Water Storage Tanks

1994 ◽  
Vol 116 (2) ◽  
pp. 94-99 ◽  
Author(s):  
J. H. Davidson ◽  
D. A. Adams ◽  
J. A. Miller
Keyword(s):  
Water Storage ◽  
Fluid Mixing ◽  
Test Duration ◽  
Drop Tube ◽  
Storage Tanks ◽  
Vertical Temperature ◽  
Solar Water ◽  
Dimensionless Coefficient ◽  
The Moment ◽  
Limiting Values

A dimensionless coefficient is developed to characterize the level of mixing in solar water storage tanks. The MIX number, based on the height weighted energy, or moment of energy, in the tank, ranges from 0 to 1, with 0 representing a perfectly stratified (unmixed) tank and 1 representing a fully mixed tank. Limiting values are based on theoretical determinations of the maximum and minimum values of the moment of energy in a tank without mixing and a tank with complete mixing, respectively. Use of the new MIX number is illustrated by experimental data obtained in a 372-liter storage tank operated with both a conventional drop-tube inlet and a rigid, porous stratification manifold. The initial tank temperature profile, the temperature of the water entering the tank, and test duration are varied in three testing schemes. Fluid mixing is quantified by measured vertical temperature profiles and the dimensionless MIX number.

Performance of Rigid Porous Stratification Manifolds With Interpretation for Off-Design Operation

2013 ◽  
Author(s):  
Shuping Wang ◽  
Jane H. Davidson
Keyword(s):  
Performance Indicator ◽  
Water Storage ◽  
Operating Conditions ◽  
Hot Water ◽  
Storage Tanks ◽  
Solar Water ◽  
Inlet Flow Rate ◽  
Wide Range ◽  
Collector Efficiency ◽  
D Model

Thermal stratification of solar water storage tanks improves collector efficiency and provides higher quality energy to the user. A crucial aspect of maintaining stratification is preventing mixing in the tank, particularly during solar charging and hot water draws. An effective and simple approach to flow control is an internal stratification manifold. In this paper, the performance of the rigid porous manifold, which consists of a series of vertical hydraulic resistance elements placed within a perforated tube, is considered for charging operation. A 1-D model of the governing mass, momentum, and energy conservation equations is used to illustrate the procedure for designing a manifold and to explore its performance over a broad range of operating conditions expected in solar water storage tanks. A manifold performance indicator (MPI) is used to evaluate the effectiveness of the manifold relative to an inlet pipe positioned at the top of the tank. The rigid porous manifold improves the stratification in the tank over a wide range of operating conditions unless the inlet flow rate is significantly reduced from the design point.

Applied Research of Solar Water Heater Integrated with Modern Architecture

2013 ◽  
Vol 756-759 ◽  
pp. 4492-4496
Author(s):  
Bo Yang Zhang ◽  
Ya Hui Xie ◽  
Shun Xiang Sun
Keyword(s):  
Water Storage ◽  
Heating System ◽  
Modern Architecture ◽  
Solar Water Heater ◽  
Storage Tanks ◽  
Water Heating ◽  
Water Heater ◽  
Solar Water Heating ◽  
Solar Water ◽  
Solar Water Heating System

This paper describes the application forms of building integrated with solar energy. We explain a solar water heating system; its solar collectors and water storage tanks are placed together. We discuss another solar water heating system, its solar collectors are placed together but its water storage tanks are placed in every resident's home. This paper also introduces the wall-hung SWH and the application of solar refrigeration and solar heating. At last we analyze the problems of the development of solar water heater integrated with modern architecture.

Performance of Rigid Porous Stratification Manifolds With Interpretation for Off-Design Operation

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Shuping Wang ◽  
Jane H. Davidson
Keyword(s):  
Performance Indicator ◽  
Water Storage ◽  
Operating Conditions ◽  
Hot Water ◽  
Storage Tanks ◽  
Solar Water ◽  
Inlet Flow Rate ◽  
Wide Range ◽  
1D Model ◽  
Collector Efficiency

Thermal stratification of solar water storage tanks improves collector efficiency and provides higher quality energy to the user. A crucial aspect of maintaining stratification is preventing mixing in the tank, particularly during solar charging and hot water draws. An effective and simple approach to flow control is an internal stratification manifold. In this paper, the performance of the rigid porous manifold, which consists of a series of vertical hydraulic resistance elements placed within a perforated tube, is considered for charging operation. A 1D model of the governing mass, momentum, and energy conservation equations is used to illustrate the procedure for designing a manifold and to explore its performance over a broad range of operating conditions expected in solar water storage tanks. A manifold performance indicator (MPI) is used to evaluate the effectiveness of the manifold relative to an inlet pipe positioned at the top of the tank. The rigid porous manifold improves the stratification in the tank over a wide range of operating conditions unless the inlet flow rate is significantly reduced from the design point.

System Modeling of Greenhouse Type Solar Water Heater

Solar Energy ◽  
2005 ◽  
Author(s):  
Yiping Wang ◽  
Wei Tian ◽  
Yonghui Liu ◽  
Zhiyong Yang ◽  
Li Zhu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Water Temperature ◽  
Flat Plate ◽  
Air Temperature ◽  
Water Storage ◽  
Solar Water Heater ◽  
Storage Tanks ◽  
Water Heater ◽  
Solar Water ◽  
New System

A Greenhouse type solar water heater has been built to evaluate the thermal performance of the new system and to extend the application field of thermosyphon solar heating system. The system consists of flat plate absorbers, greenhouse, water storage tanks and connection pipes. The greenhouse has dimensions of 34.6m in length and 9.2m in width. Ten cylindrical tanks of 0.5m in diameter and 1.5m in length and the flat plate absorbers with total area of 138m2 are connected in parallel. The roof and south wall of the greenhouse are made from polycarbonate which has high light transmission and low heat transmission and other walls are from Sandwiched color steel plates which are thermally insulated from the ambient environment. The water storage tanks, the flat plate absorbers and the connection pipes, which need no other insulation because of greenhouse effect, are placed in the greenhouse. The experimental data includes solar radiation, wind speed, ambient temperature, greenhouse air temperature, storage water temperature, and absorber temperature et al. To investigate new system performance, it is necessary to develop mathematical model which is different from models of traditional thermosyphon solar water heater because the new system combines natural circulation system and greenhouse technology. The transient thermal model of greenhouse type solar water heater is derived, which is based on energy balance of the flat plate absorbers, the floor, the air in the greenhouse, the roof, and the storage tank. Greenhouse air temperature and storage water temperature are predicted and mass flow rate is calculated according to the balance between the frictional pressure drop and pressure due to density differences around the thermosyphon circuit. It shows that the experimental data fit well with the estimated values according to the new mathematical models.

Fabric Stratification Manifolds for Solar Water Heating

1994 ◽  
Vol 116 (3) ◽  
pp. 130-136 ◽  
Author(s):  
J. H. Davidson ◽  
D. A. Adams
Keyword(s):  
Thermal Stratification ◽  
Operating Conditions ◽  
Forced Flow ◽  
Test Duration ◽  
Drop Tube ◽  
Water Heating ◽  
Solar Water Heating ◽  
Solar Water ◽  
Inlet Flow Rate ◽  
Natural Fabrics

The level of thermal stratification that can be maintained in forced-flow, direct solar water-heating systems using a fabric manifold is studied in a 372-liter tank with an inlet flow rate of 0.07 1/s. A rib-knit, lightweight, spun-orlon acrylic is the most effective manifold material in a comparative study of 13 synthetic and natural fabrics. Thermal stratification (or more appropriately mixing) in the tank equipped with this acrylic manifold is compared to the level of stratification achieved using a rigid, porous manifold and a conventional drop-tube inlet. Initial tank temperature profile, temperature of the water entering the tank, and test duration are varied in three testing schemes. Comparison of vertical temperature profiles and height-weighted energy stored in the tank indicate that under realistic operating conditions, the fabric manifold is 4 percent more effective than the rigid manifold, and 48 percent more effective than the conventional drop-tube inlet.

Experimental investigation of the night heat losses of hot water storage tanks in thermosyphon solar water heaters

2011 ◽  
Vol 3 (3) ◽  
pp. 033103 ◽  
Author(s):  
Ioannis Michaelides ◽  
Polyvios Eleftheriou ◽  
George A. Siamas ◽  
George Roditis ◽  
Paraskevas Kyriacou
Keyword(s):  
Experimental Investigation ◽  
Water Storage ◽  
Heat Losses ◽  
Hot Water ◽  
Storage Tanks ◽  
Solar Water ◽  
Water Heaters ◽  
Solar Water Heaters

scholarly journals The effect of household storage tanks/vessels and user practices on the quality of water: a systematic review of literature

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Musa Manga ◽  
Timothy G. Ngobi ◽  
Lawrence Okeny ◽  
Pamela Acheng ◽  
Hidaya Namakula ◽  
...  
Keyword(s):  
Systematic Review ◽  
Water Quality ◽  
Storage Tank ◽  
Grey Literature ◽  
Water Storage ◽  
Storage Tanks ◽  
Water Storage Tank ◽  
Hygiene Practices ◽  
Quality Of Water ◽  
Vessel Material

Abstract Background Household water storage remains a necessity in many communities worldwide, especially in the developing countries. Water storage often using tanks/vessels is envisaged to be a source of water contamination, along with related user practices. Several studies have investigated this phenomenon, albeit in isolation. This study aimed at developing a systematic review, focusing on the impacts of water storage tank/vessel features and user practices on water quality. Methods Database searches for relevant peer-reviewed papers and grey literature were done. A systematic criterion was set for the selection of publications and after scrutinizing 1106 records, 24 were selected. These were further subjected to a quality appraisal, and data was extracted from them to complete the review. Results and discussion Microbiological and physicochemical parameters were the basis for measuring water quality in storage tanks or vessels. Water storage tank/vessel material and retention time had the highest effect on stored water quality along with age, colour, design, and location. Water storage tank/vessel cleaning and hygiene practices like tank/vessel covering were the user practices most investigated by researchers in the literature reviewed and they were seen to have an impact on stored water quality. Conclusions There is evidence in the literature that storage tanks/vessels, and user practices affect water quality. Little is known about the optimal tank/vessel cleaning frequency to ensure safe drinking water quality. More research is required to conclusively determine the best matrix of tank/vessel features and user practices to ensure good water quality.

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