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Numerical Simulation Study On Regenerative Stage Of Flat Type Solar Water Heater Storage Water Tank

Posted on:2015-10-18Degree:MasterType:Thesis
Country:ChinaCandidate:J Y YangFull Text:PDF
GTID:2133330452452304Subject:Agricultural Biological Environmental and Energy Engineering
Abstract/Summary:PDF Full Text Request
Due to the instability of solar radiation and solar radiation and heat load ofinconsistency, a heat storage water tank is common in people’s life. It is one of themost important energy storage elements. The solar water heater under the heataccumulation stage, the quantity of useful heat that can be a tank store is an importantfactor to measure the quality of tank design. A good tank design can not only reducethe collector inlet temperature, improving the efficiency of the collector,also canincrease the hot water can be used.To analyse thermal stratification degree, this article chooses the commonly usedhousehold several water tank of solar hot water system in the south China as a model,this article adopts the numerical simulation method of combining the experimentstudied the heat storage water tank.The research content in this paper is summarized as follows:Firstly, under the same flow rate, conduct a heat storage phase experiment fordifferent height of the upper circular tube on the tank, and measured the temperatureof the water flow out from the circular tube outlet. On the analysis of the resultsfound that circular tube height is higher, the time of the circular tube outlettemperature began to heat up is longer, and ultimately outlet temperature is higher.Secondly, a comparative study is carried out by numerical simulation on thesame dimensions and structures tank. Find the trends presented in the dischargingtemperature profiles obtained by experiments and numerical simulated are basicallythe same, indicating that the developed numerical models can be used to simulatetanks.In addition, the numerical simulation research on different tube height anddifferent upper circulation tube flow of heat storage tank that circulation tube insertsfrom bottom or side has been carried out. And analyze temperature field in the heatstorage tank that circulation tubes, which on the same side and different, insert fromside. Get the temperature distribution and stratification inside the tank, andquantitatively analyze temperature stratification of the water tank by using non-dimensional exergy parameters. The results show that under the same conditionsthe mix water feature of heat storage tank that circulation inserts from bottom issuperior to form side. The higher the height of the circular tube on the hot water tank,storage tank dimensionless exergy value is smaller; the tank stratification degree ishigher.With increasing inlet flow rate, increasing the degree of mixing of hot and coldwater within the tank, especially when the fluid flow circulating in the inlet pipewhen the turbulent state, the degree of mixing of hot and cold water inside the tankcompared to the laminar flow state of the mixed hot and cold water aggravated mixedcase. With the increase of inlet velocity, degree of hot and cold water mixing isincreasing in the tank,, and degree of hot and cold water mixing is more intenseespecially when the circular tube inlet fluid flow in the turbulent state than underlaminar flow state. There is a litter effect on the temperature stratification in the heatstorage tank that circulation tubes, which on the same side and different, insert fromside.Finally, this paper compared the performance of mix water of three kinds oforifice of circular tube: the common tube orifice, variable diameter tube orifice andwedge tube orifice. The results show that the performance of mix water under thecommon tube orifice is the best, variable diameter tube orifice and wedge tube orificecannot improve the performance of mix water.
Keywords/Search Tags:Heat Storage Water Tank, Three-dimensional Numerical Simulation, Performance of Mix Water, Thermal Stratification, Dimensionless Exergy
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