The main purpose of this research project was to do a comparative study, by identifying a testing methodology for transient conditions, through which to allow the expression of the relative thermal performance of two DSWH collectors in comparison. The study started off by considering literature about Solar Domestic Water Heaters and National Standards-based test methods, most of which were for Steady State testing conditions. Thereafter establishing a testing methodology and setup, identifying factors to be considered. The results were analyzed and conclusions drawn. The hypothesis was to allow the reduction in the complexity of testing equipment and methods, and by doing transient condition testing and still utilizing the Hottel-Whillier-Bliss relationship as a way of expressing efficiency, the hypothesis was proven.

The study found that investing in solar water heater system (SWH) would be an economically, socially and environmentally viable option to implement within urban households; in which the hot water demand, volume of hot water consumption, water heating costs, and electricity tariffs are high. Investing in solar water heater technology should be the key focus of South African government; in order to enhance the wellbeing of the ordinary citizens. The study made use of the qualitative research approach to investigate solar water heater drivers and barriers; from the perspective of energy consumers. This will be achieved by focusing on the major drivers and barriers that consumers consider when making decisions on adoption of solar water heater system. It is believed that solar water heater drivers and barriers substantially influence the potential and urban development thereof. Solar heat is utilized in the residential sector for heating water for bathing, cleaning, washing and cooking food, but its availability is limited (Arora & Arora, 2013). Renewable energy has become a wild card internationally and regionally because of the technical, economic and environmental barriers affecting the disadvantaged individuals.

No description available.

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.

Consumer exposure to opportunistic pathogens in potable water systems poses a significant challenge to public health as manifested by numerous cases of pneumonia, non-tuberculosis lung disease, and keratitis eye infections. Water utilities have extensive understanding in control of heterotrophic and coliform bacteria re-growth in water distribution systems via disinfection, control of assimilable organic carbon (AOC), and biologically degradable organic carbon (BDOC). However, much little is known about the effect of AOC on the proliferation of heterotrophic bacteria and pathogens within premise plumbing. This thesis is the first systematic examination of opportunistic pathogen persistence and amplification in simulated glass water heaters (SGWH) as a function of influent organic matter concentration. The role of plumbing conditions that may internally generate AOC is critically examined as part of this evaluation. Strong correlations were often observed between influent organic matter and heterotrophic bacteria in effluent of SGWH as indicated by 16S rRNA gene abundance (average R2 value of 0.889 and 0.971 for heterotrophic organisms and 16S rRNA respectively). The correlation was strongest if water turnover was more frequent (every 48-72 hours) and decreased markedly when water changes were less frequent (stagnation up to 7 days). No simple correlations were identified between the concentration of pathogenic bacteria (L. pneumophila, M. avium, A. polyphaga, and H. vermiformis) and AOC, although correlations were observed between M. avium and TOC over a limited range (and only for a subset of experiments). Indeed, there was little evidence that Legionella and Acanthamoeba proliferated under any of the conditions tested in this work. Parallel experiments were conducted to examine the extent to which factors present in premise plumbing (e.g. sacrificial magnesium anode rods, cross-linked polyethylene, nitrifying bacteria, and iron) could influence water chemistry and influence growth of bacteria or specified pathogens. Although these factors could strongly influence pH, dissolved oxygen concentrations, and levels of organic matter (e.g. iron, magnesium, nitrifying), there was no major impact on effluent concentrations of either heterotrophic bacteria or premise plumbing pathogens under the conditions investigated. While additional research is needed to confirm these findings, at present, there is no evidence of correlations between organic matter and pathogen concentrations from SGWH under conditions tested. Substantial effort was also invested in attempting to identify SGWH and oligotrophic nutrient conditions that would consistently support L. pneumophila and A. polyphaga amplification. A review of the literature indicates no prior examples of large scale amplification of these microorganisms at nutrient levels commonly found in synthesized potable water. It is likely that a complex combination of abiotic and biotic factors (i.e. micronutrients, necrotrophic growth, ambient water temperature, disinfectant type and dose, plumbing materials, water usage patterns), which are not yet fully understood, control the amplification and viability of these pathogenic organisms in premise plumbing systems. / Master of Science

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Solar energy is a time dependent, high-temperature radiant energy resource. The utility of a solar thermal energy system increases if the hot temperature source is available when it is needed most. This is realized by the thermal storage of the solar energy. Thermal storage gives greater versatility to a solar energy system by decoupling the heat source from the heat sink. A large quantity of energy may be stored during the melting process in a phase change material (PCM) within a small temperature range. This molten PCM can then deliver its absorbed heat at a constant temperature in a heating application. In this study a phase change storage system (PCS) is developed and proposed for a solar water heating application. This PCS system stores more heat per unit mass than would be possible with water across the same temperature range. The heat transfer rate in and out of many PCMs is slow because of the low thermal conductivity of the PCM. However, heat transfer enhancers (HTE), such as heat pipes and fins may be added to enhance heat absorption and heat removal rates. Heat pipes have the inherent capability to transfer heat at high rates across large distances, even where the temperature difference is small. In this thesis a description is given of a PCS system consisting of paraffin wax as the PCM and which uses rectangular heat pipes in conjunction with aluminium fins to enhance heat transfer. The storage design is modular and each module has the characteristic that enhanced heat transfer in and out of the PCM is possible when the module is heated or cooled. It also has the capability to quickly absorb or alternatively to supply heat at a nearly constant temperature during the phase change of the module. A rectangular module was designed and built. The module was then analysed under controlled heat absorption and heat removal cycles. The heat up experiment involved an electrical kettle as the hot temperature source. The heat sink was a mains water heat exchanger. The experimental results were compared to those of a transient numerical model, which calculates theoretically how the module will perform thermally under the given test conditions. The numerical model of the experimental set-up was validated when it was found that the numerical model results resemble the experimental results. The numerical model was then adapted to simulate a novel solar water heater (SWH) with an additional PCS container. The improvement over previous designs is that the additional storage container can be heated to a higher temperature than the allowable geyser temperature. The system also heats up and cools down at a faster rate than would be possible without the HTEs. From the numerical simulation the size and performance of such a system is determined. This numerical analysis indicated that a phase change storage system in a SWH application will increase the hot water delivered by a given solar collector and geyser by increasing the storage capacity and by heating up the geyser overnight for early morning hot water use. / AFRIKKANSE OPSOMMING: Son energie is ‘n tyd afhanklike, hoë temperatuur radiasie energiebron. Die bruikbaarheid van ‘n sontermiese energie sisteem verhoog indien die hoë temperatuur bron beskikbaar is wanneer dit die meeste benodig word. Dit kan verwesenlik word deur die sonenergie termies te stoor. Termiese storing bied groter veelsydigheid aan ‘n sontermiese stelsel deur effektief die hittebron te ontkoppel van die hitte sink. ‘n Groot hoeveelheid energie kan, gedurende die smeltingsproses in ‘n faseveranderingsmateriaal binne ‘n nou temperatuurband gestoor word. Hierdie gesmelte materiaal kan weer op sy beurt in die waterverhittingstoepassing, die geabsorbeerde hitte teen ‘n konstante temperatuur oordra. In hierdie studie word ‘n sonwaterverwarmer stelsel wat aangepas is deur ‘n addisionele latente hittestoor daaraan te heg, voorgestel. Hierdie faseverandering hittestoor kan meer hitte stoor as wat water in dieselfde temperatuur band sou kon. Die hitteoordrag tempo na en van baie van die faseveranderingsmateriale (FVM) is egter as gevolg van die lae termiese geleidingskoëfisient, stadig. Hierdie eienskap kan gelukkig verbeter word deur hittepype en hitteoordrag verhogings materiaal soos vinne by te voeg. Hittepype het die inherente eienskap om hitte teen ‘n hoë tempo oor groot afstande, oor te dra, selfs oor ‘n klein temperatuurverskil. In hierdie tesis word ‘n ondersoek rakende ‘n faseverandering storingsisteem wat bestaan uit paraffien was as die FVM en reghoekige hittepype wat te same met met aluminium finne gebruik word om die hitteoordragtempo te verhoog, beskryf. Die stoorontwerp is modulêr en elke module het die kenmerk van hoë hitteoordrag na en van die FVM. Die module het verder ook die eienskap om vining hitte te absorbeer of hitte af te gee. Dit gebeur teen ‘n konstante temperatuur gedurende die faseverandering van die FVM. Presies so ‘n reghoekige module is ontwerp en gebou en onder beheerde hitte absorbering- en hitte verwyderingsiklusse analiseer. Tydens die verhittings eksperiment is ‘n elektriese ketel van gebruik gemaak wat gedien het as die hoë temperatuur bron. Die hitte sink was ‘n hitteruiler wat kraanwater van ‘n konstante hoogte tenk ontvang het. Die resultate van die volledige toets is met die resultate van tydafhanklike numeriese model vergelyk. Hierdie numeriese model bereken teoreties wat die module se storing verrigting onder gegewe toets omstandighede sal wees. Die numeriese model se resultate het goed vergelyk met die resultate van die eksperimente. Die numeriese model van die module is toe aangepas om ‘n sonwaterverwarmer met addisionele stoortenk wat fase verandering materiaal gebruik, te simuleer. Hierdie ontwerp is anders as vorige ontwerpe in die sin dat hoër temperature as wat die warmwatertoestel kan hanteer, in die faseverandering storingstenk, bereik kan word. Die sisteem kan ook as gevolg van die hitteoordrag verhoging materiaal, vinniger verhit of afkoel en teen ‘n vinniger tempo. Die simulasie van die sonwaterverwarmer met FVM word gebruik om die grootte en verrigting van die sisteem te bepaal. Hierdie numeriese model toon aan dat wanneer ‘n addisionele faseverandering storingstelsel in ‘n sonwaterverwarmer toepassing gebruik word, die warm water wat die verbruiker uit die sisteem kan verkry, kan verhoog. Die rede hiervoor is dat meer hitte gestoor kan word, wat beskikbaar gemaak word aan die warm water tenk.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering in the School of Electrical and Information Engineering, July 2017 / This dissertation presents the design and testing of controllers intended to provide au- tonomous demand response, through the use of water heater loads and grid frequency measurements. The controllers use measured frequency as an indication of the strain on a utility grid, which allows demand side management to be isolated from any form of central control. Water heaters can operate as exible loads because their power consump- tion can be dispatched or deferred without directly impacting users. These properties make it possible to control individual water heaters based on the functioning of the grid, rather than end user input. The purpose of this research is to ultimately provide a low- cost alternative to a traditional Smart Grid, that will improve the resilience of a grid without negatively impacting users. The controllers presented here focus on ensuring that users receive hot water, while attempting to reduce any imbalance between power generated and power consumed on the grid. Simulations of these controllers in various situations highlight that while the controllers developed respond suitably to variations in the grid frequency and adequately ensure end users receive hot water, the practical bene t of the controllers depends largely on the intrinsic characteristics of the grid. / CK2018

Thesis (MPA.) --University of Limpopo, 2016 / Refer to the document

Today's utilities face new challenges due to the continually increasing penetration of residential solar and other distributed, stochastic generation sources. In order to maintain balance and stability in the grid without building costly, large-scale generation plants, utilities are turning to distributed energy resources for use in demand response programs. Demand response is a cost-efficient way to balance grid load/generation without the need for increased capital investment in traditional generation resources. Demand response programs are excellent exploiters of end-user devices that otherwise further accentuate the daily load curve and thus, add to the difficulties created by daily load peaks. Electric water heaters are excellent candidates for use in demand response programs for a variety of reason. One, electric water heaters represent a large portion of daily household loads due to their high nominal power ratings (1.5 kW - 5.5kW), and frequent use estimated to account for approximately one third of all daily residential power demand. Two, they are composed of strictly resistive elements, which greatly simplifies modeling, aggregation and control. And third, they can be used for load "shedding" during periods of high electrical demand as well as load "absorbing" during periods of excess generation due to their thermal storage capabilities. With improved access and control, electric water heaters could become a major distributed energy resource for utilities. In order to properly control and use a distributed energy resource, it is important to know how these resources operate and their patterns of behavior in different environments. This thesis presents a single-element, single mass electric water heater model for analyzing the effectiveness of using electric water heaters as distributed energy resources and for participation in demand response programs. The CTA-2045 communication protocol was used for testing demand response signals. The electric water heater is modeled in Python and the communication pathway was built in C++ and Python.

Energy efficient technologies and renewable energy technologies are becoming less of a novelty in the American energy mix. These technologies offer the promise of a decreased dependence on foreign oil, considerable savings of energy bills, and protections for the environment. Despite the many potential benefits, these technologies face many barriers to adoption. The lack of renewable energy technologies and energy efficient technologies is particularly damaging in the State of Hawaii, where 90% of energy needs are met with imported fossil fuels. This report focuses on the current energy policies in Hawaii and the barriers to the incorporation of renewable energy technologies and energy efficient technologies, specifically solar water heaters. / text