In the process industries, cooling capacity is an important enabler for the facility to manufacture on specification product. The cooling water network is an important part of the over-all cooling system of the facility. In this research a cooling water circuit consisting of 3 cooling towers in parallel, 2 cooling water pumps in parallel, and 11 heat exchangers in parallel, is modelled. The model developed is based on first principles and captures the dynamic, non-linear, interactive nature of the plant. The modelled plant is further complicated by continuous, as well as discrete process variables, giving the model a hybrid nature. Energy consumption is included in the model as it is a very important parameter for plant operation. The model is fitted to real industry data by using a particle swarm optimisation approach. The model is suitable to be used for optimisation and control purposes. Cooling water networks are often not instrumented and actuated, nor controlled or optimised. Significant process benefits can be achieved by better process end-user temperature control, and direct monetary benefits can be obtained from electric power minimisation. A Hybrid Non-Linear Model Predictive Control strategy is developed for these control objectives, and simulated on the developed first principles dynamic model. Continuous and hybrid control cases are developed, and tested on process scenarios that reflect conditions seen in a real plant. Various alternative techniques are evaluated in order to solve the Hybrid Non-Linear Control problem. Gradient descent with momentum is chosen and configured to be used to solve the continuous control problem. For the discrete control problem a graph traversal algorithm is developed and joined to the continuous control algorithm to form a Hybrid Non-Linear Model Predictive controller. The potential monetary benefits that can be obtained by the plant owner through implementing the designed control strategy, are estimated. A powerful computation platform is designed for the plant model and controller simulations. / Thesis (PhD)--University of Pretoria, 2019. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted

From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / Wastewater reuse options for the Phoenix area include: agricultural irrigation, fish and wildlife enhancement, ground water recharge, industrial processing and coiling water, recreation, cooling water for power generation stations, and exchanging effluent for additional water supplies. Consideration is given to effluent reuse potential as a commodity to exchange for water suitable for domestic water supply. This exchange would result in yet additional reuses of the water as title to the effluent could be assured by contracts and agreements.

Project Completion Report, OWRT Project No. A-043-ARIZ / Agreement No. 14-31-0001-4003 / Project Dates: July 1973 - June 1974 / Acknowledgment: The work upon which this report is based was supported in large part by funds provided by the United States Department of the Interior, Office of Water Research and Technology, as authorized under the Water Resources Research Act of 1964. / A growing demand for energy production in Arizona has increased the need for assembling and analyzing water resource information relative to energy production, especially electrical power generation. Unit water requirements for cooling of electrical plants, combined with projections of future electrical power demands in Arizona, provide a perspective on future quantities of water needed for cooling. Probabilistic estimates of storage reserves in Arizona groundwater basins indicate that some prospective plant sites can be supplied from groundwater for the 30 -year life of the plant, while others cannot. An estimate of comparative cost for supplying groundwater versus municipal wastewater for cooling electrical plants at selected sites in Arizona showed that use of wastewater would result in considerable savings over use of groundwater, at all sites considered.

Tato práce je zaměřena na systém vodního vstřikování a způsoby zajištění dostatečného množství potřebné kapaliny pro správný chod tohoto systému. Jedním zajímavým a nezávislým řešením je využití odpadních produktů motoru, a to vodní páry produkované spalováním paliva. Pro zajištění kondenzace je nutné zchlazení výfukových plynů pod rosný bod páry, což lze zajistit opatřením výfukového potrubí chladiči. Vzniklý kondenzát je pak potřeba efektivně oddělit od proudu plynů a zachytit. Návrh takovéhoto systému vychází z reálně naměřených dat a jeho následným ověřením pomocí CFD simulace.

Regnvatteninsamling för olika syften är väl utbrett världen över och har blivit allt mer populärt i takt med ett förändrat klimat. Idag används regnvatten på många håll till hushållsanvändning men intresset har även ökat inom industrisektorn. Syftet med examensarbetet var att undersöka möjligheterna för att samla in och lagra regnvatten samt ersätta dricksvatten i Sandvik AB:s kylsystem. Detta genomfördes dels genom att undersöka vilka tillstånd som krävs för att samla in regnvatten, dels genom att föreslå en magasinutformning, storlek samt lokalisering av denna utifrån flödesberäkningar och dels genom att undersöka hur temperaturen förändras hos regnvatten i ett magasin för att bedöma dess funktion som kylvatten. I studien har först flödesberäkningar med avseende på effektivitet (hur mycket regnvatten som kan ersätta dricksvatten) simulerats för en nederbördsfattig, nederbördsrik respektive genomsnittlig tidsperiod. Därefter konstruerades två modeller i HYDRUS-1D, vilka representerade regnvattenmagasin med omgivande jord vid en lodrätt och en horisontell värmetransport. Enligt studien bedöms verksamheten idag ha alla tillstånd som krävs och behöver inte några ytterligare tillstånd. Valet av magasin blev ett avsättningsmagasin under mark med hänsyn till lokala förutsättningar. Hela anläggningen kan maximalt nå en effektivitet på 44 % under ett nederbördsrikt år med dagens totala förbrukningsdata för dricksvatten i kylsystemet samt totala takytan. Jämförelsen mellan olika lokaliseringar inom anläggningen ledde till att Stålverk 64 föreslogs samt presenterades närmare och utifrån dess effektivitet valdes magasinstorleken 1500 m3 för de 30 000 m2 som Stålverk 64 har i takyta. Effektiviteten för Stålverk 64 blev under ett nederbördsrikt år 77 %, ett genomsnittligt år 64 % och under ett nederbördsfattigt år 54 %. Värmesimuleringarna visade på att det är ytterst få dygn om året som regnvatten som lagras i ett avsättningsmagasin riskerar att vara för varmt för att användas som kylvatten. Slutsatsen är att Sandvik AB har goda möjligheter att samla in regnvatten för att ersätta dricksvatten i kylsystemet men behöver utveckla större lagringsmöjligheter för att uppnå en ännu högre effektivitet. / Rainwater harvesting is used for different purposes all over the world and has increased in popularity in line with climate change. Rainwater is today widely used for households, but interest has also increased within the industrial sector. The aim with this thesis was to investigate rainwater harvesting as a substitute for the use of drinking water in Sandvik´s cooling system. This was examined by investigating legislation concerning rainwater harvesting, different designs and sizes of storage systems and locations that would be suitable for storing rainwater. Also, temperature changes in a rainwater storage system were examined to estimate rainwater´s use for cooling. Firstly, calculations of water flow were simulated with respect to efficiency (how much rainwater that can substitute for drinking water) for three periods with different amounts of precipitation. Secondly, two models were implemented in HYDRUS-1D to represent a storage system for rainwater with surrounding soil with a vertical and horizontal heat transport. The results indicate that the industry has required permits for rainwater harvesting. Taking local conditions into account, an underground storage was chosen to store the rainwater. The entire facility can have a maximum efficiency of 44 % during a year with a high amount of precipitation with the total roof area and today’s consumption of drinking water in the cooling system. A comparison between different locations within the facility resulted in a more specific presentation of Stålverk 64 with respect to its efficiency; 1500 m3 was proposed as the storage size for the roof area of 30 000 m2. The efficiency for Stålverk 64 varied between 54-77 % for years with different amounts of precipitation. Simulated heat transport demonstrated that the risk for excessive water temperatures in an underground storage was low and with elevated temperatures occurring only a couple of days per year. The conclusion is that Sandvik AB has good opportunities for rainwater harvesting to substitute drinking water in the cooling system but need to develop higher capabilities for storage systems to achieve higher efficiency.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / An examination of potential water sources for power plant cooling in Arizona is presented along with information pertinent to Arizona's future water needs relative to electrical usage growth. It has been projected that Arizona's peak electrical power demands in 1980 and 1990 will exceed that of 1970 by some 5000 megawatts and 16000 megawatts of electricity respectively. At present, the bulk of the electrical energy generated in the western states originates at hydroelectric installations. Utilization of nuclear reactors for power generation requires a larger amount of cooling water than is required for a comparable fossil-fueled plant. It is suggested that the utilization of reclaimed wastewater for cooling purposes is a viable and attractive alternative to groundwater pumpage from both economic and ecological standpoints. Savings arise from conservation of fuel normally required for well pumps, costs of well construction are not required, quantities of fresh water should be released for consumption by alternate users, and a previously unused resource would be effectively recycled.

HETA utbildningar i Härnösand har ett ångkraftverk för undervisningssyfte som kyls ner med vatten från en underjordisk bassäng på cirka 329 m³. Syftet med detta examensarbete har varit att undersöka hur bassängen med spillvärmen från kraftverket kan användas som ett säsongslager i kombination med en befintlig 7,8 kW värmepump för att värma upp maskinhallen i deras laboratoriebyggnad. Ett kalkylark skapades i Microsoft Excel för att kunna genomföra beräkningarna. Då mätdata saknades skapades ett simulerat scenario baserat på temperaturstatistik och körschema för kraftverket från år 2017. Transmissionsförluster beräknades för bassängen och maskinhallen. För bassängen användes mestadels observationsdata och kännedom hos personalen, medan maskinhallens isolering i huvudsak fick uppskattas efter byggår. Resultatet blev att värmepumpen med aktuellt körschema kunde täcka cirka 45 % av maskinhallens årliga uppvärmningsbehov. Av de 276 GJ som tillfördes genom kylning av ångkraftverket under ett år beräknades endast 2,7 % kunna utnyttjas till uppvärmning av maskinhallen, på grund av för lite isolering i bassängen. De största begränsningarna för högre täckning och större nyttjande av spillvärmen bedömdes vara placeringen i tid av kraftverkets körningar, och värmepumpens effekt. Om körningarna skulle förläggas i huvudsak till november–april och värmepumpen ersättas med en på 10 kW, skulle 74 % av värmebehovet kunna täckas och över 18 % av spillvärmen utnyttjas. Andra saker som förbättrad isolering i bassängen och större vattenvolym bedömdes också kunna förbättra bassängens kapacitet som energilager. / HETA Education in Härnösand has a steam power plant for educational purposes which is cooled with water from a 329 m³ underground basin. The purpose of this thesis has been to examine how the basin with the waste heat can be used as seasonal thermal energy storage with an existing 7.8 kW heat pump in order to heat the machine room of their lab building. A spreadsheet was created in Microsoft Excel in order to carry out the calculations. As no measurement data was available, a simulated scenario was created based on temperature statistics and the operating schedule for the power plant from the year 2017. Transmission losses were calculated for the basin and the machine room. For the basin, mostly observational data and knowledge among the staff were used, while the insulation for the machine room mainly had to be estimated based on the construction year. The result was that the heat pump, with the current operating schedule, could cover around 45% of the yearly heating demand of the machine room. Of the 276 GJ that were added through cooling of the power plant during a year, according to calculations, only 2,7% could be used for heating the machine hall, due to lacking insulation in the basin. The greatest limitations for achieving a higher heating coverage and a greater usage of the waste heat were assessed to be the placement in time of the power plant runs, and the effect of the heat pump. If the runs would be placed mainly in November–April, and the heat pump replaced with a 10 kW one, around 74% of the heating demand could be covered and 18 % of the waste heat used. Other things, such as increased insulation in the basin and larger water volume were also assessed to be able to increase the capacity of the basin as heat storage.

e master's thesis clarifies the concept of trigeneration and the principle of absorbing cooling. Compare the advantages and disadvantages of this method of manufacture cool with compressor cooling. It presents an overview of the implementation of a developing cold absorption and performance. Acquainted with the types of absorption chillers of the two leading suppliers, their characteristics and existing applications of these refrigeration units in operation in the Czech Republic and abroad. It also assesses the possibility of using these units in conjunction with a cogeneration unit powered by internal combustion engine. It follows from the economic assessment of costs and income of the absorption chillers and compressor chillers and on concrete examples and an assessment of the effectiveness of the various options.