Under 2014 stod industrin i Sverige för nästan 40% av den totala energianvändningen. Stål- och metallindustrin står för den näst största delen efter massa- och pappersindustrin. En stor del av energin går förlorad som restvärme och betraktas ofta som avfall. Användning av restvärme ger ett minskat behov av primär värme samt minskade utsläpp av CO2. I många fall går restvärmen att använda till fjärrvärme om den har tillräckligt hög temperatur. Det här examensarbetet har tagits form av en fallstudie på stålindustrin Sandvik. Syftet med arbetet är att ta fram en energibalans för en av byggnaderna inne på industriområdet. Ett till syfte är att undersöka om det finns möjlighet att återanvända restvärme från kylsystemet. Byggnaden som har undersökts heter Norra stegvalsverket och verksamheten som bedrivs där är stegvalsning av rör. För att nå målet med arbetet har en litteraturstudie genomförts, fallstudie som har innehållit en del mätningar av flöden och temperaturer samt en mängd intervjuer. För att ta fram en energibalans krävs det att byggandens energiflöden kartläggs. Den tillförda energin kommer i form av el, ånga och internvärme. Energin som bortförs är transmission, ventilation, kylvatten och oavsiktlig ventilation. Arbetet har begränsats till en byggnad och inga tekniska lösningar har undersökts. Resultatet från detta arbete visar att temperaturen på kylvattnet är för låg för att brukas till fjärrvärme om den inte uppgraderas till en högre temperatur. Ett annat användningsområde är att förvärma ventilationsluften med kylvattnet. Arbetet visar också att det finns för lite detaljerad information beträffande elanvändningen. Problemet upptäcktes i arbetets slutskede vilket gjorde att det inte fanns tid att göra ytterligare mätningar. Detta gör att det inte ger en rättvis bild hur energin fördelas i Norra stegvalsverket. För att utveckla detta arbete krävs en noggrann undersökning av elanvändning för att ta reda på exakt hur mycket el Norra stegvalsverket förbrukar. En studie skulle även kunna utföras om det finns tekniska och ekonomiska möjligheter att förvärma ventilationsluften med kylvattnet. / In 2014, industrial operations in Sweden consumed nearly 40% of the total energy use. The steel and metal industry uses the second largest amount of energy in the industrial sector, only the pulp and paper industry uses more. A large part of the energy is waste heat and is often considered as waste. I many cases the waste heat can be used for district heating if it has sufficiently high temperature. This thesis has been taken as a case study at the steel industry Sandvik. The aim of this study is to develop an energy balance for one of the buildings at the plant. Another purpose is to investigate whether there is a possibility to reuse the heat from the cooling system. The building that has been investigated is called Norra stegvalsverket, which is a cold-pilger mill. To reach the goal with this study, a literature study has been conducted, a case study containing some measurements of flows and temperatures, as well as a variety of interviews. To generate an energy balance, it is required that the energy flow of the building is mapped. The energy that is added is electricity, steam, and internal heat. The energy that the building consumes is transmission, ventilation, cooling water, and uncontrolled ventilation. The study has been limited to one building and no technical solutions have been investigated. The result of this work show that the temperature of the cooling water is too low to be used for district heating unless it is upgraded to a higher temperature. One possible application for the cooling water is to preheat the ventilation air. The study also shows that there is too little detailed information regarding the use of electricity in the building. The problem was discovered at the end of the project, which meant that there was no time to make further measurements. Due to this problem, the study does not give a fair picture how the energy is distributed in Norra stegvalsverket. To develop this study, a thorough investigation of the electricity usage is required to find exactly how much electricity the building uses. A study could also be carried out to find out if there are technical and economic opportunities to preheat the ventilation air with the cooling water.

Submitted in fulfilment of the requirements for M.Tech.: Electrical Engineering, Durban University of Technology, 2017. / Industrial plants are excellent sources of waste heat and provide many opportunities for energy harvesting using thermo-electric principles. A thermoelectric generator (TEG) is utilized in this study for harvesting expended heat from various sources. The main challenge associated with this type of technology lies in the creation of a sufficient thermal gradient between the hot side and the cold side of the TEG device. This is necessary for the module to generate an appreciable quantity of electrical energy. The performance of the TEG generator is tested using different configurations, different heat sources and different cooling methods. Heat sources included electrically driven devices, gas, biomass and gel fuel. Expended heat from different sites within an industrial environment was also chosen for operating the TEG device. The power produced by the generator is sufficient to operate low power LED lights, a DC radio receiver and a cellular phone charger. / M

In most previous studies that have been conducted on converting waste heat energy from exhaust gases into useful energy, the engine waste heat recovery system has been placed along the exhaust flow pipe where the temperature differs from the temperature just behind the exhaust valves. This means that an important fraction of the energy from the exhaust gases is still lost to the environment. The present work investigates the potential thermodynamic analysis of an integrated exhaust waste heat recovery (EWHR) system based on a Rankine cycle on an engine's exhaust manifold. The amount of lost energy contained in the exhaust gases at the exhaust manifold level, at average temperatures of 500 °C and 350 °C (for petrol and diesel), and the thermodynamic composition of these gases were determined. For heat to occur, a temperature difference (between the exhaust gas and the working fluid) at the pinch point of 20°C was considered. A thermodynamic analysis was performed on different configurations of EWHR thermal efficiencies and the selected suitable working fluids. The environmental and economic aspects of the integrated EWHR system just behind the exhaust valves of an internal combustion engine (ICE) were analysed. Among all working fluids that were used when the thermodynamic analysis was performed, water was selected as the best working fluid due to its higher thermal efficiency, availability, low cost and environmentally friendly characteristics. Using the typical engine data, results showed that almost 29.54% of exhaust waste heat can be converted. This results in better engine efficiency and fuel consumption on a global scale by gaining an average of 1 114.98 Mb and 1 126.63 Mb of petrol and diesel respectively from 2020 to 2040. It can combat global warming by recovering 56.78 1 011 MJ and 64.65 1 011 MJ of heat rejected from petrol and diesel engines, respectively. A case study of a Volkswagen Citi Golf 1.3i is considered, as it is a popular vehicle in South Africa. This idea can be applied to new-design hybrid vehicles that can use the waste heat to charge the batteries when the engine operates on fossil fuel. / Dissertation (MSc)--University of Pretoria, 2016. / Mechanical and Aeronautical Engineering / MSc / Unrestricted

<div>With the United States being the world’s second largest consumer of primary energy, research into areas of significant consumption can provide large impacts in terms of the global energy consumption. Buildings account for 41% of U.S. total energy consumption with the residential sector making up a majority. Household appliances account for the second largest site energy consumption at 27%, after the HVAC system for the U.S. residential sector. Federal appliance standards have been instrumental in improving efficiencies but have been increasing aggressively to where it is unknown what suitable technologies can support this rate of increase. Thermally integrating residential appliances by leveraging waste heat recovery goes outside standards and has not been adequately explored by connecting all residential appliances. Limited studies exist focused only on single appliances connected to waste heat recovery or being thermally integrated. Preliminary modeling on waste heat availability from five major appliances, namely refrigerator-freezer, clothes dryer, clothes washer, dishwasher, and cooking oven was conducted. Conservative estimates predict the total amount of heat recovery to be around 2,000 kWh/year; clothes dryer - 137 kWh/year, clothes washer - 60 kWh/year, 1,500 kWh/year- refrigerator-freezer, 27 kWh/year – dishwasher, and 178 kWh/year – cooking oven. The cooking oven presents technical challenges coupled with safety concerns. The clothes dryer and refrigerator-freezer can deliver useful water temperatures and reduce compressor power consumption, up to 20%. The dishwasher has better opportunity as a heat sink to offset the internal heater, 0.17 kWh of electricity/cycle for heating wash water. The clothes washer drains large volumes of water available for heat recovery and can offset the impact of using high temperature washes with improved wash performance. </div><div>Modelica appliance models have been developed for four of these five appliances. The Modelica models capture individual use and the predictions of the RF and DW were compared against available experimental data. The individual models have been connected to a simple storage tank model to simulate the integrated appliance system. An integrated appliance prototype was designed and fabricated for the collection of experimental data. Comparisons made between the experimental data and the integrated appliance simulation results adjusted the modeling approach and improved agreement with collected data. After tuning, ideal modifications to each appliance are made and reflected in a new integrated model. A parametric study is conducted on ideal improved, thermally capable appliances under a 1-week schedule for two different tank sizes. For 300L and 150 L tank sizes, the appliance total energy for the week is roughly 30.5 kWh compared to a baseline appliance system with no thermal resource sharing at 33.8 kWh. At an electricity cost of $0.15/kWh, the cost savings for the integrated system is a little over $0.40/week. Furthermore, the savings is completely diminished when considering the required auxiliary power to support the exchange of heat between each appliance and storage tank. The impact of tank size should be explored further to identify a critical tank size where the system savings is no longer available. Accounting for all the domestic hot water needs of the home would generate an improved picture where integrated appliances have technical feasibility. </div><div><br></div>

The combination of the continuously growing demand of energy in the world, the depletion of oil and its sharp price increase, as well as the urgent need for cleaner and more efficient fuels have boosted the global trade of liquefied natural gas (LNG). Nowadays, there is an increasing interest on the design philosophy of the LNG receiving terminals, due to the fact that the existing technologies either use seawater as heating source or burn part of the fuel for regasifying LNG, thus destroying the cryogenic energy of LNG and causing air pollution or harm to marine life. This investigation addresses the task of developing novel systems able to simultaneously regasify LNG and generate electric power in the most efficient and environmentally friendly way.    Existing and proposed technologies for integrated LNG regasification and power generation were identified and simple, efficient, safe and compact alternatives were selected for further analysis. A baseline scenario for integrated LNG regasification and power generation was established and simulated, consisting of a cascaded Brayton configuration with a typical small gas turbine as topping cycle and a simple closed Brayton cycle as bottoming cycle. Various novel configurations were created, modeled and compared to the baseline scenario in terms of LNG regasification rate, efficiency and power output. The novel configurations include closed Rankine and Brayton cycles for the bottoming cycle, systems for power augmentation in the gas turbine and combinations of options. A study case with a simple and compact design was selected, preliminarily designed and analyzed according to characteristics and costs provided by suppliers. The performance, costs and design challenges of the study case were then compared to the baseline case. The results show that the study case causes lower investment costs and a smaller footprint of the plant, at the same time offering a simple design solution though with substantially lower efficiencies.

Waste-heat-to-power (WHP) recovers electrical power from exhaust heat emitted by industrial and commercial facilities. Waste heat is available in enormous quantities. The U.S. Department of Energy estimates 5-13 quadrillion BTUs/yr with a technical potential of 14.6 GW are available and could be utilized to generate power by converting the heat into electricity. The research proposed here will define a system that can economically recover energy from waste heat through a thermal regenerative electrochemical system. The primary motivation came from a patent and the research sponsored by the National Renewable Energy Laboratory (NREL). The proposed system improves on this patent in four major ways: by using air/oxygen, rather than hydrogen; by eliminating the cross diffusion of counter ions and using a dual membrane cell design; and by using high concentrations of electrolytes that have boiling points below water. Therefore, this system also works at difficult-to-recover low temperatures. Electrochemical power is estimated at 0.2W/cm2, and for a 4.2 M solution at 1 L/s, the power of a 100 kW system is 425 kW. Distillation energy costs are simulated and found to be 504 kJ/s for a 1 kg/s feed stream. The conversion efficiency is then calculated at 84%. The Carnot efficiency for a conservative 50% conversion efficiency is compared to the ideal Carnot efficiency. Preliminary work suggests an LCOE of 0.6¢/kWh. Industrial energy efficiency could be boosted by up to 10%. Potential markets include power stations, industrial plants, facilities at institutions like universities, geothermal conversion plants, and even thermal energy storage.

A common industrial ventilation and pollution problem results when a thermally buoyant polluted plume of air must be exhausted away from a work area to allow achievement of air pollution standards. Generally, a close fitting canopy hood is one of the most effective means of exhaust containment; however, physical restrictions or the operation itself often prevent such an arrangement, and a hood located to the side of the operation is required. This arrangement requires the exhaust to bend and contain the vertically rising plume with a horizontal sweep of exhaust air across the surface of the operation. A review of available literature revealed a lack of the necessary theory and data needed to design a side draft hood based on plume dynamics. The purpose of this study, then, is to develop the theory relating the side draft hood size and required exhaust volume to the hot source characteristics and to test the theory in the laboratory.

No description available.

By partly replacing the use of primary energy sources with waste heat recovery, climate and environmental goals for the future will be closer at hand. This thesis investigates the waste heat potential of Alfa Laval’s vacuum brazing furnaces in Ronneby and alternative ways of integrating the furnace’s waste heat into the building’s HVAC system. The main challenge was the low-temperature qualities associated with the cooling water, which constituted an obstacle to recovering waste heat without any additional equipment, such as a heat pump. Tests and analyses performed in this thesis are, therefore, mainly aimed at raising the temperature quality of the cooling water. A test was conducted on the cooling system to calculate the energy losses with regards to the cooling water. In one 11-hour cycle, 1546 kWh of electricity was used to heat the furnace. Out of that, 1360 kWh was cooled off to the atmosphere. Additionally, a test on the furnace’s clean-up cycle was performed. The maximum cooling water temperature reached during this test was 44 C. This shows excellent potential in the possibility of recovering the waste heat without any additional equipment. Further, this thesis aims to broaden the knowledge around areas concerning increased cooling water temperatures, which, during the writing, seemed to have a gap in documented sources. The results of this thesis indicate that a temperature quality increase of the furnaces’ cooling water is possible. Cooling system changes have also been suggested, which is necessary for an efficient and safe heat recovery.

Energy demands are projected to continue increasing over the next decade, which is prompting a change towards higher efficiencies and better utilization of the current energy supply. Thermal waste energy, a prominent inefficiency during any process, can be converted to electrical energy or re-purposed for low-grade energy needs, such as hot water and space heating/cooling. Naturally ventilated chimneys, driven by buoyancy differences between the exhaust gases and the surrounding air, prove to be a source of waste heat. The challenge of waste heat recovery from naturally ventilated exhaust networks is the reduction in buoyancy effects and increase in flow restrictions within the network. This research study will focus on understanding the effects of waste heat recovery and the associated exhaust control devices on the performance of a naturally ventilated exhaust network and the accompanying appliance(s). To investigate the effects, a nodal network methodology using mass and energy conservation principles was adapted for exhaust networks to develop a one-dimensional computational model. In contrast to previous exhaust flow design methodologies, this method solves for the thermal input of the appliance and the associated flow rates, temperature, and pressures via the appliance set point temperature and exterior conditions, such as outside temperature and pressure. Using empirical correlations for heat transfer and pressure loss coefficients of appliance and exhaust components, the computational model was validated through experimental testing of an exhaust network used in the development of a waste heat recovery system called TEG POWER (Thermal Electrical Generator Pizza Oven Waste Energy Recovery). The experimental facility was constructed to investigate the exhaust network with and without the TEG POWER system, along with exhaust control devices. These devices included an exhaust throttling valve and a draft hood to induce dilution air into the chimney. To investigate the individual effects of the devices, experimental testing was conducted at an oven temperature of 300°F (148.9°C), 500°F (260°C), and 600°F (315.6°C) with varying degrees of throttling and/or dilution air. The mass flow measurements were calculated using an energy balance technique validated against a two-way energy balance and well-established heat transfer and pressure loss correlations of the heat exchanger. The experimental mass flow, temperature, and draft pressure results were compared against the respective computational predictions and found to be within a ±10% agreement. The application of the exhaust control techniques with and without waste heat recovery is highly dependent on the objective(s), such as reducing natural gas consumption, and the constraint(s), such as a minimum chimney temperature, placed on the exhaust network design. Using the computational model, a design methodology was proposed to meet the objective(s) within the constraints of the exhaust network. To test the design methodology, a case study was performed with the objective to minimize oven natural gas consumption with a TEG POWER system in relation to a baseline appliance solely fitted with a draft hood. Within the constraints, the methodology was able to identify the appropriate degree of throttling and dilution air intake to minimize natural gas consumption. With the inclusion of the TEG POWER system, the case study showed a potential reduction in natural gas consumption by up to 18% (1.7 L/min) and 13% (3 L/min) at 300 and 600°F oven operating temperatures, respectively. The implementation of the control technique allowed the oven to minimize the intake of dilution air by up to 70% and maintain operational stability during exterior fluctuations in temperature and pressure. The implementation of the waste heat recovery device captured up to 1.0 and 2.7 kW, or a natural gas equivalent of 1.9 and 5 L/min, at 300 and 600°F oven operating temperatures respectively. Implemented into the 8,000 pizza restaurants across Canada, the TEG POWER system would reduce total natural gas consumption by up to 65.5 million cubic meters, which is enough to heat 24,000 Canadian homes, and reduce CO2 output by 112,000 metric tonnes. / Thesis / Master of Applied Science (MASc)