A detailed analysis of the heat transfers and fluid flows within a direct thermosyphonic solar-energy water-heater has been undertaken. The collector energy equations when cast in a two-dimensional form enabled heat transfer and thermal capacitance effects to be simulated accurately at the small flow rates encountered commonly in such systems. An investigation of thermocline relaxation processes within the store indicated negligible mixing at the store inlet over a wide range of Richardsons numbers (43,608 < Ri < 729,016). Thermal relaxation under conditions of no flow was shown to be due predominantly to axial conduction along the store wall. The use of an appropriate non-isothermal friction factor correlation when calculating frictional losses in the collector's riser pipes, produced predicted steady-state flow rates which were corroborated experimentally to within 2%. An indoor test facility, monitored and controlled by a microcomputer, enabled 'real' operating conditions to be simulated. The predicted responses of the system to identical conditions showed good agreement with the corresponding experimental observations, the predicted heat delivery being within 2.8% of the measured value. A technique for correlating the daily performances of thermosyphon solar-energy water-heaters has been developed. The five dimensionless groups which form the basis of the correlations and the functional relationships between these groups were derived from an analytical solution of a linear first-order differential transient heat balance carried out on a generic system. Thermal performance data used in the correlations was generated by the numerical simulation using representative U. K. hourly weather data and operating conditions. The minimum amount of data required to establish a characteristic curve for an individual system was found to be thirty days. Using such a curve, the total annual solar fraction agreed with that predicted by the high level model to within 3%. Two universal curves were determined in which the gradients of characteristic curves were correlated against the derived dimensionless groups. The accuracy of the resulting two-stage algorithm in determining annual solar fractions was established as ranging from 5.5% for predominantly multiple-pass systems to a mean of 10.5% for single-pass systems.

This report is concerned with the performance of solar hot water units for laboratory and field use. A solar unit is defined as a system consisting of a collector, storage tank, piping system and controls. Older unites typically employ the thermosyphon principle (gravity) while more recent models use a water pump to circulate the water. Basically, the collector absorbs solar radiation and transfers thermal energy to the water flowing in the collector tubing. From the collector, the fluid is pumped to the storage tank at which point the hot water is available for usage. A literature search revealed that very little information was available concerning test procedures. The National Bureau of Standards (NBS) has generated proposed test procedures for separate testing of the collector and storage tank, but they do not include testing of the total system. The only other suggested test procedure found was by Stotter and Robinson, these authors include a discussion of the total system. Stotter and Robinson along with (NBS) provided the starting point for this report. In the report it is shown that qualitative properties are equally as important as quantitative properties. Quantitative properties are defined as temperature, flowrate, solar radiation or insolation, wind velocity and direction. Qualitative properties are defined as shade, weather resistance, corrosion resistance, location and maintenance. To determine which solar unit properties would be useful in comparing performance values, test reports along with the other references on solar unit testing were studied. After a review of all the reference material the following performance parameters were obtained and are believed to be of use in comparing solar units. These parameters are discussed in detail in the text of the report. 1. nth, the practical thermal efficiency 2. pSTOR, the heat storage coefficient 3. Q, the solar unit capacity 4. Ceff, capacity efficiency. It was found from the error analysis that the recommended instrumentation and test procedure, presented herein, should result in less than ± 10% error in the calculation of performance parameters. Temperature measurement error was found to be the largest contributor to the overall error. It is recommended that the test procedure herein be used for Florida Technological University testing of laboratory and field solar units, and the future work be performed to develop a method of rating solar units.

Sunshine, air and water are the vital elements to the human. This study investigated the insolation and solar radiation in Kaohsiung city. Solar radiation on the horizontal and declined plane was calculated. Sun shadow model for urban buildings was constructed for computing accumulated sunshining hours. Horizontal and vertical building shadows were displayed in ArcGIS ¡V the GIS software. Raster-based data model was used to analyze the effect of sun shadow shading by neighbour buildings. And the effect of shadow shading for solar water heater was also investigated. According to the results, minor installation error of orientation and decline angles of solar panel will not cause major energy loss. And the distance between the buildings¡Bthe height difference and the orientation between buildings are most important factors which affect optimal installation location of the solar water heater. If there are buildings located to the south, southeast and southwest, and the stories difference between buildings is over three, the installing location should be moved toward north. If buildings are next to each others and the variation of height is large, the efficient of receiving solar radiation will be deteriorated. The larger is the distance between buildings, the better the energy received.

The purpose of this study is to investigate the performance of a spherical solar collector by using numerical and experimental methods. For this analysis, equations were obtained by choosing appropriate control volumes in the system and applying The First Law of Thermodynamics. The experiments were realized at four different mass flow rates and non-flow situation. For the numerical simulation of the system, a computer program in Mathcad was written. Another computer program in Mathcad was written for the variation of the absorbed solar radiation through out the day. Finally, the performance of the spherical solar collector is compared theoretically to that of flat plate solar collectors.

abstract: Improving the conditions of schools in many parts of the world is gradually acquiring importance. The Green School movement is an integral part of this effort since it aims at improving indoor environmental conditions. This would in turn, enhance student- learning while minimizing adverse environmental impact through energy efficiency of comfort-related HVAC and lighting systems. This research, which is a part of a larger research project, aims at evaluating different school building designs in Albania in terms of energy use and indoor thermal comfort, and identify energy efficient options of existing schools. We start by identifying three different climate zones in Albania; Coastal (Durres), Hill/Pre-mountainous (Tirana), mountainous (Korca). Next, two prototypical school building designs are identified from the existing stock. Numerous scenarios are then identified for analysis which consists of combinations of climate zone, building type, building orientation, building upgrade levels, presence of renewable energy systems (solar photovoltaic and solar water heater). The existing building layouts, initially outlined in CAD software and then imported into a detailed building energy software program (eQuest) to perform annual simulations for all scenarios. The research also predicted indoor thermal comfort conditions of the various scenarios on the premise that windows could be opened to provide natural ventilation cooling when appropriate. This study also estimated the energy generated from solar photovoltaic systems and solar water heater systems when placed on the available roof area to determine the extent to which they are able to meet the required electric loads (plug and lights) and building heating loads respectively. The results showed that there is adequate indoor comfort without the need for mechanical cooling for the three climate zones, and that only heating is needed during the winter months. / Dissertation/Thesis / Masters Thesis Architecture 2015

abstract: The complicated, unpredictable, and often chaotic hot water usage pattern of typical households severely limits the effectiveness and efficiency of traditional solar hot water heater systems. Similar to large scale concentrating solar power plants, the use of thermal energy storage techniques to store collected solar energy as latent heat has the potential to improve the efficiency of solar hot water systems. Rather than being used to produce steam to generate electricity, the stored thermal energy would be used to heat water on-demand well after the sun sets. The scope of this thesis was to design, analyze, build, and test a proof of concept prototype for an on-demand solar water heater for residential use with latent heat thermal energy storage. The proof of concept system will be used for future research and can be quickly reconfigured making it ideal for use as a test bed. This thesis outlines the analysis, design, and testing processes used to model, build, and evaluate the performance of the prototype system. The prototype system developed to complete this thesis was designed using systems engineering principles and consists of several main subsystems. These subsystems include a parabolic trough concentrating solar collector, a phase change material reservoir including heat exchangers, a heat transfer fluid reservoir, and a plumbing system. The system functions by absorbing solar thermal energy in a heat transfer fluid using the solar collector and transferring the absorbed thermal energy to the phase change material for storage. The system was analyzed using a mathematical model created in MATLAB and experimental testing was used to verify that the system functioned as designed. The mathematical model was designed to be adaptable for evaluating different system configurations for future research. The results of the analysis as well as the experimental tests conducted, verify that the proof of concept system is functional and capable of producing hot water using stored thermal energy. This will allow the system to function as a test bed for future research and long-term performance testing to evaluate changes in the performance of the phase change material over time. With additional refinement the prototype system has the potential to be developed into a commercially viable product for use in residential homes. / Dissertation/Thesis / Masters Thesis Engineering 2015

No description available.

This report includes development of an already designed solar water heater. The product shall be constructed in a way that it will suit a manufacturing line in Kampala, Uganda. To find the most suitable design for each area a research was carried out which included study visits, interviews and background reading. It provided the following results: Regarding the attachment of in- and outgoing pipes from the water tank many methods were taken into consideration and it was found that the best and most suitable way for this case is to weld the fittings using a weld robot. Regarding the fitting of the acrylic, a suitable solution is to make a flange when vacuum forming the plastic casing to further support the design. This could also be used to waterproof the case by using a sealing material. A suggestion of using pre-molded PU-foam is also presented. Regarding the ability to open the case for maintenance, two solutions were recommended. Either the use of spire clips or having the clips integrated into the casing. Regarding the calculation of material usage when deep drawing the tank and collector, it is possible to do a reasonably accurate assumption. The complicated design in this product makes the estimation less accurate. It is recommended that test draws are done and often the machine producer has more precise numbers. Regarding the coloring of the collector; chemical coloration is not possible on a galvanized surface. The method used is painting, either with powder coating or with wet paint.

In Cape Town, South Africa, households' acces to modern and clean energy services needs to be increased. However, use of coal-powered electricity stresses the environment and power cuts create an urgent need to reduce the demand. Solar water heaters (SWH) could enable increasing access and affordability of energy services in the townships without stressing the environment or increasing the demand for coal-powered electricity. However, it is an expensive solution and the majority of the city-level efforts still target the high-consuming households. The benefits for the poor households from using a SWH could though outweigh the high capital investements and meet the needs of the city's environmental management. The results from this study of 20 households showed that by having an affordable, clean and reliable source of energy for heating water, households were able to use more warm water for bathing and reduce their use of electricity and paraffin. This resulted in improvements in health and quality of life. Also, households' general spending on energy was reduced, which for some enabled an increase in income-generating activities. The use of solar-heated showers was found to be restricted by the issue of sharing and it is argued that the benefits would be greater if each households had their own solar water heater. The estimated increase in water use might raise questions of the solution's future feasibility. Despite this, it can be argued that the changes in the households' energy and water use are likely to result in significant improvements in the households' well-being which could also benefit the city as a whole.

Water heating in a typical home in the U.S. accounts for a significant portion (between 14% and 25%) of the total home's annual energy consumption. The objective of considerably reducing the home's energy consumption from the utilities calls for the use of onsite renewable energy systems. Integral Collector Storage (ICS) solar domestic water heating systems are an alternative to help meet the hot water energy demands in a household. In order to evaluate the potential benefits and contributions from the ICS system, it is important that the parameter values included in the model used to estimate the system's performance are as accurate as possible. The overall heat loss coefficient (Uloss) in the model plays an important role in the performance prediction methodology of the ICS. This work presents a new and improved methodology to determine Uloss as a function of time in an ICS system using a systematic optimal control theoretic approach. This methodology is based on the derivation of a new nonlinear state space model of the system, and the formulation of a quadratic performance function whose minimization yields estimates of Uloss values that can be used in computer simulations to improve the performance prediction of the ICS system, depending on the desired time of the year and hot water draw profile. Simulation results show that predictions of the system's performance based on these estimates of Uloss are considerably more accurate than the predictions based on current existing methods for estimating Uloss.