Thesis (M.S.)--Virginia Polytechnic Institute, 1952. / Vita. Includes bibliographical references (leaves 73-75). Also available via the Internet.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / This study presents an intelligent Hot Water Cylinder (HWC) usage profiling system to provide peak demand side management and improve HWC efficiency in a typical household. In this research HWCs will be referred to as geysers. Research was done into various techniques available to improve energy efficiency in South Africa, as well as the different sectors South Africa's electricity supplier, Eskom, has highlighted where improvements in energy efficiency can be made. From this it was decided to refine the scope of the project to the residential sector, and more importantly geyser. A typical geysers operation and power consumption was researched and analysed to determine where efficiency improvements could be made. A system was required that would reduce the amount of energy consumed by the geyser, and provide the consumer with hot water at the same time. Based on the research it was decided to design a profile based geyser controller. The profiling system comprised of a PIC microcontroller, four digital temperature sensors and a time keeper used to determine individually based hot water usage profiles for the home. The profile was based on three parameters, namely the frequency (repetitiveness) of hot water being drawn, the length of the draw period, and the time of day when the water was drawn. Once the profile had reached a 90% accuracy, the profile implemented itself. Based on the profile, the controller then regulated the temperature of the geyser according to the demand of the household, without manual intervention. If the household's routine were changed, the profile would adapt itself accordingly. The controller is therefore fully intelligent and continues to refine the profile on a day to day basis. By introducing the profile based controller, the monthly average geyser temperature was reduced, reducing the amount of standing losses, which in torn reduced the total amount of energy consumed by the geyser. The profile controller was designed to aid in the reduction of the energy demand of geysers on the power grid. This will benefit both the consumer as well as Eskom, as Eskom will have a reduced power load, and the consumer will have a reduced electricity bill. The results of the experiments are shown, as well as a comparison between calculated versus measured results, to justify the accuracy of the calculations.

M.Ing. / The refrigerant R22, which is currently used in hot water heat pumps, delivers a maximum hot water temperature of 60 to 65 °C. This temperature is adequate for domestic use, but low if compared to temperatures that can be delivered by fossil fuels and direct electric resistance systems. This limits the potential applications of hot water heat pumps. In this study two analytical design methodologies were developed that can be used to predict the performances of water-to-water heat pumps. The first design methodology is for a pure R22 heat pump and the second for a non-azeotropic refrigerant mixture of R22 and R142b. These design methodologies were used as tools together with three methods of comparison to determine the influence of a non-azeotropic refrigerant mixture (R22 mixed with R142b) on the performance of a hot water heat pump. It was found in certain cases that, depending on the concentrations, not only are increased hot water temperatures possible but also an improved heating capacity, an improvement in the coefficient of performance and a reduction in pressure ratio of the compressor.

Thesis (M.S.)--Ohio University, November, 1993. / Title from PDF t.p.

A conceptual end use model for residential water demand and return flow is presented in this thesis. The model requires a unique description of a single residential stand in terms of all its end-uses. The end-uses include toilet flushing, bathing and showering, garden watering, leaks, et cetera. Various parameters describe each of the end-uses. The model predicts five components relating to water demand and wastewater flow at a residence: indoor water demand, outdoor water demand, hot water demand, wastewater flow volume and concentration of solutes in the wastewater. Twelve monthly results are calculated, for each of the five components, to provide a typical seasonal pattern as well as an annual value. The large number of input parameters in an end-use model allows for powerful and detailed analysis. The parameters required to populate the model are discussed and guideline values are presented. The end-use model is used to conduct a sensitivity analysis of each independent parameter for each of the five individual model components. The elasticity and sensitivity is determined at a base point with respect to each parameter for all five results. A research significance index is also devised to integrate the elasticity and availability of data for each parameter. The result is a prioritised list of the most critical parameters for each of the five components, which are the ones that should receive the focus for future study and data recording. The parameters are combined to obtain a list of the overall most important parameters in the model for all components combined, and based on a combination of the elasticity-based rank and the sensitivity based rank. The five most important parameters are the household size, toilet flush frequency, toilet flush volume, the washing machine event frequency and the volume of leaks on a stand. The practical application of the model is illustrated. The researchers first apply the model to mimic a few commonly accepted characteristics of water demand. The effectiveness of some specific water demand management measures are evaluated by adjusting selected model parameters. The measures include xeriscaping, the installation of dual-flush toilets, low-flow showerheads, pool ownership and pool cover use. The model also enables practitioners to obtain an insight into the water use habits of homeowners. The model forms the basis for further research work in the field. Its relatively simple structure and realistic data requirement encourages its integration into existing commercially available software suites for water and sewer system analysis and -management in the civil engineering industry in South Africa, as well as abroad. / Prof. J. Haarhoff

M.Ing. / A one-year investigation on hot water consumption was conducted in South African developed and developing communities of Johannesburg to determine the personal and household average daily consumption of hot water as well as the average hourly (in summer and in winter) and monthly patterns. The motivation for this research project was to provide to engineers and water heaters manufacturers reliable experimental data on hot water consumption from various categories of dwellings. The existing sources of information in South Africa being extremely limited and results of estimations. The necessary information was collected from hourly and monthly measurements taken by monitoring hot water systems in different dwellings including, houses (300 units), traditional houses (90 units), shacks (200 units), apartments (123 units), townhouses (90 units). For the purpose of this study, the selected (not statistically) dwellings were classified into three categories, which are: high-density dwellings representing the developing communities, medium-density and low-density dwellings which represent the developed communities. The results of measurements show that, in general, people living in developed communities (low-density dwellings) use at least 1.4 times more hot water than those of developing communities (high-density dwellings). The patterns of hot water consumption have been determined for monthly and hourly consumption. The former is divided in four sections: summer weekdays, winter weekdays, summer weekends and winter weekends. The differences between sections are the specific times of peaks and the consumption. The results of this study should be of great assistance to engineers and water heaters designers in analysing existing systems for performance improvement, and in sizing more efficient and suitable systems to South African use.

The building Norra Djurgården 43:12 on the main campus of the Royal Institute of Technology (KTH)  in Stockholm will be retrofitted as students from the exter- nal campus Haninge will be moved there. This occasion is supposed to be used to improve the facility’s energy efficiency. Potential for this exists for both the space and the water heating system. The effect of decreasing the supply temperature to the radiators was examined  based on equations for the heat transfer. It was calcu- lated that lowering the supply temperature by 5 K would reduce the space heating demand by 25 %, i.e. 94.25 MWh a−1  and avoid emissions of 9.9 t CO2 a−1. Due to high heat losses from the secondary district heating circuit on KTH property to the ground, an alternative for the domestic hot water supply at times without space heating demand, i.e. from May to September, was considered.  Two systems were designed which can completely cover the demand and were evaluated in terms of both energy and economic efficiency. The daily domestic hot water demand  as well as the peak demand were modelled especially for this purpose. A system com- prising ten flat panel solar thermal collectors with a total aperture area of 23.3 m2 and an auxiliary heat pump of 7.5 kW capacity was calculated to achieve a maximum coefficient of performance (COP) of 9.13 in June. In spite of the low operation cost, the system has a negative Net Present Value as the fixed capital investment is very high. The more competitive option is the installation of a heat pump of 12.22 kW capacity which is supposed to use waste heat from the server room.  If both the cooling power and the heating  power are considered as the benefit, the Net Present Value calculates to about 274,500 SEK, otherwise it is still almost 99,000 SEK (ap- proximately 32,000 EUR and 11,500 EUR respectively).  These figures are based on an operation cycle of one year, i.e. if the heat pump contributes to the space heating supply from October to March. Compared to the use of outside air as a heat source, the COP is increased by 83 % or 10 % respectively, depending on the definition of the benefit. The reduction in the district heating demand calculated to 24.48 MWh a−1 provided the building can be disconnected from the KTH distribution network from May to September. At the same time, emissions of 2.57 t CO2 a−1  could be avoided. In conclusion, the installation of a heat pump using waste heat from the server room appears to be a solution which is both energy efficient and economical. / Das Gebäude Norra Djurgården  43:12 auf dem Hauptcampus der Königlichen Tech- nischen Hochschule (KTH)  in Stockholm wird renoviert werden, da der Vorlesungs- betrieb des externen Campus Haninge zukünftig zum Teil dort stattfinden wird. Bei dieser Gelegenheit soll die Energieeffizienz  des Gebäudes gesteigert werden. Poten- tial hierfür besteht sowohl beim Heizen als auch in der Warmwasserbereitung. Die Auswirkungen einer verringerten Vorlauftemperatur zu den Heizkörpern wurden auf Grundlage von Gleichungen zur Wärmeübertragung betrachtet. Es wurde berech- net, dass die Verringerung der Vorlauftemperatur um 5 K den Heizbedarf um 25 % reduzieren würde, d. h. um 94,25 MWh a−1, und damit Emissionen in Höhe von 9,9 t CO2 a−1 vermieden werden könnten. Aufgrund hoher Wärmeverluste vom sekundären Fernwärmekreislauf  zum Boden auf dem Gelände der KTH wurde eine Alternative  für die Warmwasserbereitung zu Zeiten ohne Heizbedarf, d.h. von Mai bis September, in Erwägung gezogen. Zwei Systeme, welche den Bedarf vollständig abdecken können, wurden entwick- elt und sowohl auf ihre Energieeffizienz  als auch auf ihre Wirtschaftlichkeit  hin geprüft. Der tägliche Warmwasserbedarf  sowie der Spitzenbedarf  wurden eigens zu diesem Zweck modelliert. Für ein Hybridsystem, welches aus zehn Flachkollek- toren mit einer gesamten Aperturfläche von 23,3 m2  und einer Wärmepumpe mit 7,5 kW Leistung besteht, wurde eine maximale Leistungszahl von 9,13 im Juni ermittelt. Trotz der geringen Betriebskosten ist der Kapitalwert negativ, da die Investitionskosten sehr hoch sind. Die konkurrenzfähige Alternative ist die Installa- tion einer Wärmepumpe mit 12,22 kW Leistung, welche die Abwärme der Computer im Serverraum nutzen soll. Werden sowohl die Kälte- als auch die Wärmeleistung als Nutzen angesehen, berechnet  sich der Kapitalwert zu etwa 32.000 EUR, ohne Miteinbeziehung der Kälteleistung zu 11.500 EUR. Diese Zahlen beziehen sich auf einen ganzjährigen Betrieb, d. h. die Wärmepumpe trägt von Oktober bis März zur Heizleistung bei. Verglichen mit der Nutzung von Außenluft als Wärmequelle kann die Leistungszahl um 83 % bzw. 10 % gesteigert werden, je nach Definition des Nutzens. Die Verringerung des Fernwärmebedarfs wurde zu 24,48 MWh a−1 berech- net, vorausgesetzt das Gebäude kann von Mai bis September vom Verteilernetz der KTH abgekoppelt werden. Gleichzeitig ermöglicht dies Emissionseinsparungen von 2,57 t CO2 a−1. Zusammenfassend erscheint  die Installation einer Wärmepumpe, welche die Abwärme im Serverraum nutzt, als eine sowohl energieeffiziente als auch wirtschaftliche Lösung. / Byggnaden Norra Djurgården  43:12 på Kungliga Tekniska Högskolans (KTH:s) hu- vudcampus i Stockholm kommer att renoveras då studenter från den externa cam- pusen Haninge kommer att  flyttas dit. Detta tillfälle  skall nu utnyttjas  för att effektivisera byggnadens energiprestation.  Potentialen för energieffektivisering finns därtill  i både uppvärmningen och varmvattenberedningen. I detta arbete har ef- fekten av sänkt tilloppstemperatur till radiatorerna studerats.  Effekten har kvan- tifierats genom beräkningarna  med hjälp av välkända ekvationer för värmetrans- port.  Beräkningarna har visat att värmebehovet kunde minskas med 25 %, d.v.s. 94,25 MWh per år, genom en sänkning av tillopstemperaturen med 5 K. Följaktigen kunde CO2 emissionerna också minskas med ungefär 9,9 ton per år. Då värmeförlusterna från den primära fjärrvärmekretsen mellan maj och september är höga, har ett alternativ  för varmvattenberedningen för denna tidsperiod pre- senterats.  Två system har presenterats som kan fullständigt täcka behovet  och har analyserats beträffande både energieffektiviteten och lönsamhet. Det dagliga varmvattenbehovet samt spetsbehovet har modellerats just för detta syfte.  Den maxmimala värmefaktorn till ett system bestående av 10 plana solfångare med en total aperturarea (genomskinliga arean) på 23,3 m−2  och en värmepump  på 7,5 kW har uppskattats till 9,13 i juni.  Trots de låga driftskostnaderna är kapitalvärdet negativt eftersom investeringskostnaderna  var höga. Den andra lösningen innefat- tade installation av en värmepump på 12,22 kW som använder sig av spillvärmen från serverrummet. Om besparingen av både fjärrvärme och fjärrkyla  betraktas i lönsamhetsanalysen, beräknas kapitalvärdet till ungefär 247.500 SEK, respektive 99.000 SEK om bara det minskade fjärrvärmebehovet  betraktas. Dessa siffror är baserade på ett års drift, d.v.s. om värmepumpen står för uppvärmningen från ok- tober till mars. Jämfört med användningen av uteluft som värmekälla  ökar värme- faktorn med 10 %. Ökningen blir 83 % om i processens nytta inkorporeras både den värme som absorberats från serverrummet och den värme som används för varm- vattenberedning  och uppvärmning. Reduktionen i fjärrvärmebehovet har beräknats till 24,48 MWh per år, förutsatt att byggnaden kan kopplas ifrån KTH:s distribu- tionsnätverk mellan maj och september.  Samtidigt kunde CO2 emissionerna också reduceras med 2,57 ton per år. Sammanfattningsvis kan det konstaterats att instal- lationen av en värmepump,  som använder sig av spillvärmen från serverrummet, kan vara både en kostnads- och energieffektiv lösning för den undersökta byggnaden.

The following conclusions appear to have merit: 1) The heat obtained from cooling milk in a mechanical farm milk cooler may be used for preheating a quantity of water. 2) The amount of water heated and the temperature to which it is heated are functions of the heat obtainable from the milk cooler and refrigeration equipment. 3) The percentage of available heat from the condenser that is available in the water passed to the electric water heater is a function of: (a) the design of the condenser-to-water heat transfer system, (b) the size and shape of the storage tank, and (c) the losses from the storage tank. 4) The savings in cost of electric energy for operation of the electric water heater are appreciable when heat extracted from cooling milk is used to pre-heat water. In this study, the savings amounted to slightly more than 30 percent. However, a large quantity of heated water passed to the overflow tank. A savings of 54 percent could be realized when the water drawn from the pre-heat tank into the water heater was raised from 62 F - 120 F in the pre-heat tank. 5) Without the assistance of a competent refrigeration mechanic, the technical problems involved make it inadvisable for the individual farmer to attempt a conversion of current milk cooling equipment for the additional function of heating water. 6) This study indicates that greater savings may be effected with a refrigeration unit and condensing unit specifically designed for heating water, using the basic principles outlined in this study. / Master of Science