This master’s thesis deals with the issue of design heat recovery steam generator. In the first part is realized calculation of stoichiometry and further the thermal balance of the boiler. The boiler was divided on the basis of thermal analysis in two heating surfaces that have been designed separately. The thesis also includes structural design and drawings of evaporator, economizer and their compilation.

The South African electricity mix is highly dependent on subcritical coal-fired power stations. The average thermal efficiency of these power plants is low. Traditional methods to increase the thermal efficiency of the cycle have been widely studied and implemented. However, utilising the waste heat at the condenser, which accounts for the biggest heat loss in the cycle, presents a large potential to increase the thermal efficiency of the cycle. Several methods can be implemented for the recovery and utilisation of low-grade waste heat. This theoretical study focuses on replacing the traditional condenser in a fossil fuel power station with a boiling condenser (BC), which operates in a similar manner to the core of a boiling water reactor at a nuclear power plant (Sharifpur, 2007). The system was theoretically tested at the Komati Power Station, South Africa's oldest power station. The power station presented an average low-grade waste heat source. The BC cycle was theoretically tested with several working fluids and numerous different configurations. Several of the theoretical configurations indicated increased thermal efficiency of the cycle. The BC cycle configurations were also tested in two theoretical scenarios. Thirty configurations and 103 working fluids were tested in these configurations. The configuration that indicated the highest increase in thermal efficiency was the BC cycle with regeneration (three regenerative heat exchangers) from the BC turbine. A 2.4% increase in thermal efficiency was obtained for the mentioned theoretical implementation of this configuration. The working fluid tested in this configuration was ethanol. This configuration also indicated a 7.6 MW generating capacity. The increased thermal efficiency of the power station presents benefits not only in increasing the available capacity on South Africa's strained grid, but also environmental benefits. The mentioned reduction of 7.6 MW in heat released into the atmosphere also indicated a direct environmental benefit. The increase in thermal efficiency could also reduce CO2 emissions released annually in tons per MW by 5.74%. The high-level economic analysis conducted, based on the theoretically implemented BC cycle with the highest increase in thermal efficiency, resulted in a possible saving of R46 million per annum. This translated to a saving of R19.2 million per annum for each percentage increase in thermal efficiency brought about by the BC cycle. The theoretical implementation of the BC, with regeneration (three regenerative heat exchangers) from the BC turbine and ethanol as a working fluid, not only indicated an increase in thermal efficiency, but also significant economic and environmental benefits. / Dissertation (MEng)--University of Pretoria, 2016. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

An experimental study of a low-frequency transcritical thermoacoustic device has been conducted at Purdue University's Maurice J. Zucrow Laboratories. The purpose of this study was to characterize the thermoacoustic response of transcritical R-218 and asses it's feasibility for energy extraction and waste heat removal. This rig operated as a standing-wave configuration and achieved pressure amplitudes as high as 690 KPa (100 psi) at a temperature difference of 150 K and a bulk pressure of 1.3 P/P_cr(3.43 MPa). To the author's knowledge, this is the highest ever thermoacoustic pressure amplitude achieved in a non-reacting flow. The thermoacoustic response was characterized by varying temperature difference and bulk pressure parametrically. The effect of resonator length was characterized in a set of tests where resonator length and bulk pressure was varied parametrically at a single temperature difference. Finally, the feasibility for energy extraction was assessed in a set of tests which characterized the ability of the working fluid to pump itself through a recirculation line with check valves. This set of tests showed that the working fluid was able to create self-sustained circulation by inducing a pressure differential across the check valves with the thermoacoustic response. This circulation was induced while still maintaining a significant pressure amplitude, demonstrating promising results as a feasible method for energy extraction and waste heat removal.

In Sweden the industries releases about 50 TWh / year of low temperature waste heat[1], often in the form of humid air flows. Today, conventional flue gas condensation is only exploiting a minor part of the energy from these flows. It is a well-established and profit­able way of improving the efficiency of district heating plants and other boilers for wet fuels. How­ever, the condensation is only applicable when the dew point of the flue gas is above the temperature demand for the heating net. The paper industry gives a good illustration of the limitations for conventional condensation: several MW of wet air streams with dew points of 60-65 ̊ C are released but cannot be recovered since the tempe­ra­ture demand is 70-80 ̊ C for the heating net. Different technologies for more advanced waste heat recovery are developing and this report is evaluating a demonstration plant for “hygro­scopic condenser”, which uses a hygroscopic solution that allows condensation above the dew point. The hygro­scopic solution is potassium formate, which enables condensation to start about 20 ̊ C above the dew point and is sufficiently non-toxic and non-corrosive. The objective of this work is to evaluate both the equipment and the process during some initial tests at the paper mill at Holmen, Braviken. The aim is also to suggest improvements of the process, the components and the additional equipment for future continuous operation.  The equipment consists of two main parts:  a hygroscopic absorption stage and a regene­ration stage. The major part of the humid air is led into an absorption column where vapor is absorbed by the formate solution and rises its temperature. This recovered waste heat is transferred to the heating net by a plate heat exchanger. The regeneration unit is used to maintain the hygroscopic concentrations by evaporation of vapor from the formate solution (amount of absorbed vapor = amount of evaporated vapor). The regene­rator is driven by process steam from the existing 3.5 bar net. The evaporated vapor is led to a conventional condenser where the regeneration energy can be recovered and the condensate is bled off.  The recovered heat from the process (hygroscopic absorber + regeneration condenser) is used in the heating net at Holmen, Braviken (VVG-net).    The initial tests have been made during 15 hours of initial operation, when the equipment has delivered about 3 MWh in total. The tests show a good temperature performance since the dew point of the humid air has been lowered from about 60oC to 47oC. The reco­vered heat was used for heating from 65oC to about 80oC. During the initial tests the capacity has not yet reached the design values. As an example the delivered heat was measured to 280 kW where­of 46kW from absorbed vapor, 129 kW from the sensible heat in the incoming humid air and 105 kW from the regeneration. The bottle-neck parts of the equipment have been localized and will be overseen during the summer of 2011 and the process is planned to be in use during the autumn with an output capacity of 500kW. The coefficient of performance (COP) is calculated to just below 2 during normal operation but was about 2.7 in the test runs due to the high portion of sensible heat. [1]Förekomst av industriellt spillvärme vid låga temperaturer,  Ingrid Nyström, Per-Åke Franck, Industriell Energianalys AB, 2002-04-15

The purpose of the thesis is to determine the potential of lessening the high energy cost in the hospitality industry so that the industry could stay alive after a three decades of civil war in Sri Lanka. The hospitality industry is a significant contributor to the country’s economic growth. Tourism industry has much hope of recovering in the year 2010. Improved tourism would also benefit larger part of Sri Lankan population as they are directly and indirectly employed to serve the tourism industry. Sri Lanka has a high electricity production cost as it depends heavily on the imported fossil fuel. Survival of hospitality industry would depend on the manner in which the energy cost - the second highest overhead in hotels is managed. If the industry survives, Sri Lanka would receive more foreign exchange and thereby improve country’s foreign currency reserve which could contribute to high growth rate. As electricity production is mainly depending on thermal, the volatility of world crude oil prices is directly affecting the country’s electricity prices. However, low dependence on the grid would help the hospitality industry to mitigate the energy cost. As the electricity and diesel costs -the highest and the next - are considerable portions in energy cost in hospitality industry, the study aims to discuss the possible ways of mitigating such costs. Measurements done by the presenters found that the usage of electricity for air conditioning system does constitute most of the electricity consumption for a hotel whilst most of the diesel consumption is for thermal applications. If Air Conditioning (AC) can be operated without electricity and thermal applications could be operated using abundantly available alternative energy sources then the overall energy costs of hospitality industry could be reduced thereby making higher profits. This would ensure industry survives and country gets more foreign exchange.  Study and calculations done by the presenters proved that operating of generators only for electricity production is not viable, due to high fossil fuel cost, however if its high exhaust temperature which is wasted otherwise, could be utilized for operation of absorption chillier then the dependence of grid electricity for air conditioning could be minimized. Further studies also revealed that if water cooled generator is used for such purpose instead of air cooled, and then the hot water requirement of hotel also could be fulfilled, thus mitigating the dependence of fossil fuel which is used otherwise for hot water production. Study also revealed that if thermal energy could be fed with biomass- Sri Lanka being a tropical country is blessed with abundantly available biomass - then the dependency on the fossil fuel for thermal applications could be avoided. This would not only mitigate the second highest energy cost for hotels but also create less carbon foot print, more environmental friendly and produce less noxious exhaust gases thereby creating an advertisement to attract tourists who longing to support green hotels

The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO2 to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity. This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO2 emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield. The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO2 emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO2 emissions can be lowered to 45 CO2/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study. Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand. / QC 20101209

Increasing the efficiency of conventional power plants is a crucial aspect in the quest of reducing the energy consumption of the world and to having sustainable energy systems in the future. Thus, within the scope of this thesis the possible efficiency improvements for the Wärtsilä 18V50DF model gas engine based combine power generation options are investigated by recovering waste heat of the engine via Organic Rankine cycle (ORC).  In order to this, four different ORC models are simulated via Aspen Plus software and these models are optimized for different objective functions; power output and price per unit of electricity generation. These ORC models are: regenerative Organic Rankine cycle (RORC), cascaded Organic Rankine cycle with an economizer (CORCE), cascaded Organic Rankine cycle with two heat sources (CORC2) and cascaded Organic Rankine cycle with three heat sources (CORC3). In the cascaded cycle models there are two loops which are coupled with a common heat exchanger that works as a condenser for the high temperature (HT) loop and as a preheater for the low temperature (LT) loop. By using this common heat exchanger, the latent heat of condensation of the HT loop is utilized. The engine’s hot exhaust gases are used as main heat source in all the ORC models. The engine’s jacket water is utilized in the CORC2 models as an additional heat source to preheat the LT working fluid. In the CORC3 models engine’s lubrication oil together with the jacket water are used as additional sources for preheating the LT loop working fluid. Thus, the suitability of utilizing these two waste heat sources is examined. Moreover, thermodynamic and economic analyses are performed for each model and the results are compared to each other. The effect of different working fluids, condenser cooling water temperatures, superheating on cycles performance is also evaluated. The results show that with the same amount of fuel the power output of the engine would be increased 2200 kW in average and this increases the efficiency of the engine by 6.3 %. The highest power outputs are obtained in CORC3 models (around 2750 kW) whereas the lowest are in the RORC models (around 1800 kW). In contrast to the power output results, energetic efficiencies of the RORC models (around 30 %) are the highest and CORC3 models (around 22 %) are the lowest. In terms of exergetic efficiency, the highest efficiencies are obtained in CORC2 (around 64.5 %) models whereas the lowest in the RORC models (around 63 %). All the models are found economically feasible since thermodynamically optimized models pay the investment costs back in average of 2 years whereas the economically optimized ones in 1.7. The selection of the working fluid slightly affects the thermodynamic performance of the system since in all the ORC configurations Octamethyltrisiloxane (MDM) working fluid cycles achieve better thermodynamic performances than Decamethyltetrasiloxane (MD2M) working fluid cycles. However, the choice of working fluid doesn’t affect the costs of the system since both working fluid cycles have similar price per unit of electricity generation. The CORC2 models obtain the shortest payback times whereas the CORC3 models obtain the longest Thus the configuration of the ORC does affect the economic performance. It is observed from the results that increasing the condenser cooling water temperature have negative impact on both thermodynamic and economic performances. Also, thermodynamic performances of the cycles are getting reduced with the increasing degree of superheating thus superheating negatively affects the cycle’s performances. The engine’s jacket water and lubrication oil are found to be sufficient waste heat sources to use in the ORC models.

Berners är en stor aktör inom försäljning och service av bilar och transportfordon i Jämtland och Västernorrland. På sina anläggningar i Sundsvall och Östersund tillhandahåller Berners bland annat biltvättar och rekond och dessa verksamheter ger upphov till stora utsläpp av vatten och kemikalier. För att minska utsläppen har Berners installerat indunstarrening, som är en reningsteknik som bygger på att smutsigt tvättvatten förångas och farliga partiklar faller ur. Med den här tekniken elimineras nästan alla kemikalieutsläpp och ungefär 90 procent av tvättvattnet återanvänds. Indunstarrening kräver mycket energi i form av el som i dagsläget köps in. Reningstekniken ger även upphov till spillvärme i både luft och vatten som i dagsläget inte utnyttjas. Syftet med arbetet är att undersöka potentiella förbättringsåtgärder för Berners biltvättar, för att göra de befintliga och eventuella framtida anläggningar bättre. Detta genom att undersöka möjligheterna av att utnyttja spillvärme och minska behovet av köpt el, genom egenproduktion av el med solceller. Målet är att genom detta ta fram underlag för Berners när de ska besluta om eventuella förändringar av de befintliga tvättarna samt vid byggnation av nya anläggningar. Underlaget ska bestå av resultat för minskade energibehov, minskade utsläpp, minskade behov av köpt el och livstidsbesparingar för förbättringsåtgärderna. I arbetet undersöktes tre olika förbättringsåtgärder. Installation av FTX-ventilation för att värma ingående luft till en angränsande lokal med utgående luft från det rum där indunstaren är placerad, installation av en plattvärmeväxlare för att värma vätskan i en radiatorkrets med utgående destillat från indunstaren samt installation av solceller för att minska behovet av köpt el till indunstaren. Monokristallina-, polykristallina- och tunnfilmssolceller samt olika storlekar av installerad area undersöktes. Minskade energibehov beräknades för FTX och VVX, minskade behov av köpt el beräknades för solceller och minskade utsläpp av koldioxidekvivalenter samt livstidsbesparingar beräknades för alla tre förbättringsåtgärderna. Resultaten visar på att en kombination av att installera FTX, VVX och polykristallina solceller genererar de största livstidsbesparingarna och de största utsläppsminskningarna. Installation av en plattvärmeväxlare för att ta vara på spillvärme i destillat är den enskilt bästa åtgärden för att minska energibehovet. Berners kan vid installation av en eller flera av de olika förbättringsåtgärderna minska energibehoven och utsläppen från biltvättarna, minska behovet av köpt el samtidigt som de kan spara pengar. / Berners is a major player in the sale and service of cars and transport vehicles in Jämtland and Västernorrland. At its facilities in Sundsvall and Östersund, Berners provides, among other things, car washes and auto reconditioning and these operations give rise to large discharges of water and chemicals. To reduce emissions, Berners has installed evaporator treatment, which is a treatment technique based on the evaporation of dirty washing water and the fallout of dangerous particles. With this technology, almost all chemical emissions are eliminated and approximately 90 percent of the washing water is reused. Evaporator cleaning requires a lot of energy in the form of electricity that is currently purchased. The treatment technology also gives rise to waste heat in both air and water, which is currently not used. The purpose of the work is to investigate potential improvement measures for Berner's car washes, to make the existing and possible future facilities better. This is done by investigating the possibilities of utilizing waste heat and reducing the need for purchased electricity, through own production of electricity with solar cells. The goal is to thereby produce a basis for Berners when they are to decide on any changes to the existing washes and when building new facilities. The basis shall consist of results for reduced energy needs, reduced emissions, reduced need for purchased electricity and lifetime savings for the improvement measures. The work examined three different improvement measures. Installation of FTX- ventilation to heat the incoming air to an adjacent room with outgoing air from the room where the evaporator is located, installation of a plate heat exchanger to heat the liquid in a radiator circuit with outgoing distillate from the evaporator and installation of solar cells to reduce the need for bought electricity for the evaporator. Monocrystalline, polycrystalline and thin film solar cells as well as different sizes of installed area were investigated. Reduced energy needs were calculated for FTX and VVX, reduced needs for purchased electricity were calculated for solar cells and reduced emissions of carbon dioxide equivalents as well as lifetime savings were calculated for all three improvement measures. The results show that a combination of installing FTX, VVX and polycrystalline solar cells generates the largest lifetime savings, as well as the largest emission reductions. Installing a plate heat exchanger to take advantage of waste heat in distillates is the single best measure to reduce energy needs. When installing one or more of the various improvement measures, Berners can reduce the energy needs and emissions from the car washes and reduce the need for purchased electricity, while at the same time saving money.

In this paper different waste heat recovery systems are investigated for Cytiva’s solvent recyclingfacility. Currently steam is used to distill ethanol before cooling it with condenser fans. Thecooling demand varies severely, and peak demand need to be handled with smart energy storagesolutions such as hot water storage tanks or salt storage. Potential heat sinks for the waste heat arelocal heating, heating water for internal use, steam condense and electrical energy generation.Python is used to simulate results with data from Cytiva. The suggested systems are evaluatedbased on yearly performance, savings and environmental impact. A comparison between thedifferent potential systems concludes that none of the investigated solutions can handle the entirecooling demand by itself and redundancy is missing during the summer months. Whenimplemented, the final solution should be a combination of multiple systems.

Sweden aims to achieve climate neutrality by 2045. The need to immediately reduce greenhouse gas emissions in order to achieve climate targets affects industry directly. The pulp and paper sector is responsible for more than 50% of industrial energy use in Sweden. Increased energy efficiency is expected to contribute significantly to the reduction of primary energy use. The recovery and utilisation of industrial excess heat (IEH) has been identified as an important potential contribution to energy efficiency in industry. Previous research based on top-down studies has estimated the availability of IEH for entire sectors, and bottom-up results for many case studies are available. While top-down studies lack detailed information on the profile of the excess heat available, bottom-up studies have limited coverage. Detailed information about excess heat amounts and temperature levels is required for the assessment of the potential of the various heat recovery technologies that are available.  The aim of this thesis is to present, in a series of steps, methods to systematically analyse an industrial process to obtain a detailed profile of the excess heat available under various process conditions, to aggregate results that can be generalised to whole industrial sectors, and to obtain IEH recovery potentials using different technologies. The assessment of the utilisation options for IEH recovery is complemented with an analysis of system aspects that could affect profitability and global greenhouse gas (GHG) emissions. An energy-targeting procedure combined with optimisation has been applied to six case studies of kraft pulp and paper mills in Sweden. This method obtained IEH profiles that were used in a regression analysis to estimate the IEH availability and electricity generation potentials from low and medium temperature IEH using organic Rankine cycles (ORC). A comparison of profitability and global GHG emissions between ORC electricity generation using IEH and small-scale combined heat and electricity (CHP) production is presented for three energy markets. The results show that there is a potential to increase electricity generation from low and medium temperature IEH by 7–9% in the kraft mills in Sweden, depending on the level of process integration considered. The utilisation of low and medium temperature IEH for electricity generation has the potential to reduce global GHG emissions in all the energy-market scenarios considered, but if biomass is considered a limited resource, district heating (DH) deliveries can achieve higher global GHG reductions. ORC electricity generation from low and medium temperature IEH is economically viable and showed overall better profitability and GHG emissions reductions than small-scale CHP using ORCs. The economic feasibility of ORC electricity generation is less affected by external conditions and uncertainties than direct DH deliveries. / Sverige siktar på att uppnå klimatneutralitet till 2045. Behovet av att omedelbart minska utsläppen av växthusgaser för att nå klimatmålen påverkar industrin direkt. Massa- och papperssektorn står för mer än 50% av den industriella energianvändningen i Sverige. Ökad energieffektivitet förväntas i hög grad bidra till att minska primärenergianvändningen. Återvinning och utnyttjande av industriell överskottsvärme (IÖV) har identifierats som ett betydande potentiellt bidrag till energieffektivitet i industrin. Tidigare forskning baserad på top-down studier har uppskattat tillgängligheten av IÖV för hela sektorer eller regioner, och bottom-up resultat för många fallstudier finns tillgängliga. Medan top-down studier saknar detaljerad information om profilen för tillgänglig överskottsvärme, har bottom-up studier begränsad täckning och precision. Detaljerad information om överskottsvärmemängder och temperaturnivåer krävs för att bedöma potentialen hos flera värmeåtervinningstekniker. Denna avhandling syftar till att i en serie steg presentera metoder för att systematiskt analysera en industriell process för att erhålla en detaljerad profil av tillgänglig överskottsvärme under olika processförhållanden, för att aggregera resultat som kan generaliseras för hela industrisektorer, och att erhålla återvinningspotentialer för industriell överskottsvärme med hjälp av olika teknologier. Bedömningen av olika möjligheter att använda industriell överskottsvärme kompletteras med en analys av systemaspekter som kan påverka lönsamhet och globala växthusgasutsläpp. Ett energimålsförfarande kombinerat med optimering har tillämpats på sex fallstudier av massa- och pappersbruk i Sverige, med produktion baserat på sulfatmassa. Med denna metod erhålls IÖV-profiler som används i en regressionsanalys för att uppskatta tillgängligheten av IÖV och potentialen för elproduktion från låg- och medeltempererad IÖV med organiska Rankine-cykler (ORC). En jämförelse av lönsamhet och globala växthusgasutsläpp mellan elproduktion med ORC, där IÖV utgör grunden, och småskalig kombinerad värme och el (KVV) produktion presenteras för tre energimarknader. Resultaten visar en potential att öka elproduktionen från låg- och medeltempererad IÖV med 7% till 9% i sulfatmassabruken i Sverige, beroende på graden av processintegration som beaktas. Användningen av låg- och medeltempererad IÖV för elproduktion kan potentiellt minska de globala växthusgasutsläppen i alla övervägda energimarknadsscenarier. Om biomassa betraktas som en begränsad resurs, kan emellertid direkta fjärrvärmeleveranser uppnå högre globala minskningar av växthusgaser. ORC-elproduktion från låg- och medeltempererad IÖV är ekonomiskt lönsam och visade överlag bättre lönsamhet och minskade växthusgasutsläpp än småskalig ORC-kraftvärme. Den ekonomiska genomförbarheten av ORC-elproduktion påverkas mindre av yttre förhållanden och osäkerheter än fjärrvärmeleveranser.