Solar Engineering of Thermal Processes

Duffie, John A.; Beckman, W.A.

doi:10.1002/9781118671603

Cited by 3,867 publications

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“…When considering a tank that operates under large degrees of thermal stratification, water in the tank is circulated through natural convection resulting in thermal stratification. Due to this lack of water Department of Electrical, Electronic and Computer Engineering University of Pretoria circulation, when fresh water enters the tank, a thermocline 1 is created which can persist for many days trapping old water at the top of the tank and over time the old water may lose its residual disinfectants making the water prone to growing disinfectant products such as bad odours and bacteria [5,24]. This would generally occur in large water tanks where the water in the tank is much larger than the daily water usage.…”

Section: Storage Tank Parametersmentioning

confidence: 99%

“…Fig.2.1 and fig.2.2 illustrate a passive SWHS as there is no pump connected to system to control the fluid flow rate [5]. The second method uses a forced circulation SWHS (also known as an active SWHS).…”

Section: Swhs Connections and Configurationsmentioning

confidence: 99%

“…The result of this would be N differential equations that can be solved to find the temperatures of each of the nodes as a function of time. The other involves a plug flow approach, where segments of liquids at different temperatures are assumed to move through the tank, and the models keep track of the size, temperature and position of the segments [5].…”

Section: Storage Tank Parametersmentioning

confidence: 99%

“…Stratification describes the temperature difference that can exist between different levels inside a tank. A multinode approach (the tank is typically divided into N nodes) is used to characterize the energy in the tank [4,5]. 2 Reversible chemical heat storage is a technique that is based on the conversion of solar radiation into high-temperature heat.…”

Section: Research Objective and Questionsmentioning

confidence: 99%

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Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

2016

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Degree:Master of Engineering (Electrical Engineering)Keywords: Flat plate solar collector, flow rate optimization, maximum energy extraction, system thermal losses, thermal comfort.Solar water heating systems (SWHS) have fast become a suitable alternative to conventional water heating systems due to growing energy demands. A SWHS generally consists of a solar collector (which is used to convert solar radiation to heat), a water storage tank, and a flow control device such as a pump in the case of forced circulation SWHS. Extensive research and analysis on the operation and performance of these systems has been conducted, and results show that optimal flow control is an important factor that can be used to improve the performance and efficiency of SWHS.This study focuses on pump flow rate optimization for forced circulation SWHS with pipes.The system analyzed consists of an array of flat plate solar collectors, two storage tanks (one for the circulation fluid and one for the water), a heat exchanger, two pumps, and connecting pipes which are considered as one of the components of the SWHS so as to account for their thermal effects. The proposed model is developed using mainly the first and second laws of thermodynamics. The model is used to maximize the difference between the energy extracted from the solar collector and the combined sum of the energy extracted by the heat exchanger and corresponding energies used by the pumps in the primary and secondary loops. The objective function maximizes the overall system energy gain whilst minimizing the sum of the energy extracted by the heat exchanger and energy used by the corresponding pumps in the secondary loop to conserve the stored energy and meet the user requirement of water tank temperatures.The model is solved using the fmincon solver in MATLAB's optimization toolbox. When compared to other flow control techniques, in particular the most suitable energy efficient control strategy, the results of this study show a significant increase in the system's overall energy gain. The results also illustrate the effects of system pipe thermal losses for the different control strategies, hence highlighting the importance of developing a model that takes such losses into account so as to improve the overall accuracy of the model. Sonenergie-waterverwarmingstelsels (SWV) het vinnig 'n geskikte alternatief vir konvensionele waterverwarmingstelsels geword, weens die groeiende vraag na energie. 'n SWV bestaan gewoonlik uit 'n sonkollektor wat gebruik word om sonstraling om te skakel na hitte, 'n opgaartenk vir water, en 'n vloeibeheertoestel soos 'n pomp, in die geval van geforseerde sirkulasie SWV. Uitgebreide navorsing en ontleding op die werking en prestasie van hierdie stelsels is uitgevoer en die resultate toon dat die optimale vloeibeheer 'n belangrike faktor is wat gebruik kan word om die prestasie en doeltreffendheid van SWV verbeter. OPSOMMINGHierdie studie fokus op die optimering van die vloeitempo van 'n pomp vir geforseerde sirkulasie sonenergie-waterverwarmingste...

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Section: Storage Tank Parametersmentioning

confidence: 99%

Section: Swhs Connections and Configurationsmentioning

confidence: 99%

Section: Storage Tank Parametersmentioning

confidence: 99%

Section: Research Objective and Questionsmentioning

confidence: 99%

See 2 more Smart Citations

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

2016

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“…For higher efficiency, the design of collector should be such that the tilt angle can be at least changed on seasonal basis [9]. Reference [12] has given two different angles for summer and winter that, for summer the optimum tilt angle should be 10 to 15 degrees less than the latitude and for winter tilt angles should be 10 to 15 degrees more than the latitude, which can be considered as a gap as some researchers later on found that the yearly average of optimum tilt is equal to the latitude of the site [11]. Azimuth angle calculations can be done and tilt of the panel with respect to south direction (for panel in northern hemisphere) can be found out with good accuracy [13].…”

Section: Introductionmentioning

confidence: 99%

Study of Solar Tracking Angle for Dish Type Concentrating Collectors

Mehta¹,

Vyas²,

Srinivas³

et al. 2016

IJERT

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Electric car with solar and wind energy may change the environment and economy: A tool for utilizing the renewable energy resource

Liu

2014

Earth's Future

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Energy and environmental issues are among the most important problems of public concern. Wind and solar energy may be one of the alternative solutions to overcome energy shortage and to reduce greenhouse gaseous emission. Using electric cars in cities can significantly improve the air quality there. Through our analyses and modeling on the basis of the National Centers for Environment Prediction data we confirm that the amount of usable solar and wind energy far exceeds the world's total energy demand, considering the feasibility of the technology being used. Storing the surplus solar and wind energy and then releasing this surplus on demand is an important approach to maintaining uninterrupted solar-and wind-generated electricity. This approach requires us to be aware of the available solar and wind energy in advance in order to manage their storage. Solar and wind energy depends on weather conditions and we know weather forecasting. This implies that solar and wind energy is predictable. In this article, we demonstrate how solar and wind energy can be forecasted. We provide a web tool that can be used by all to arrive at solar and wind energy amount at any location in the world. The tool is available at www.renewableenergyst.org. The website also provides additional information on renewable energy, which is useful to a wide range of audiences, including students, educators, and the general public.

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Solar Engineering of Thermal Processes

Cited by 3,867 publications

References 0 publications

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

Study of Solar Tracking Angle for Dish Type Concentrating Collectors

Electric car with solar and wind energy may change the environment and economy: A tool for utilizing the renewable energy resource

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