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Thin-Film Thermoelectrics
Published in Sam Zhang, Materials for Devices, 2023
Xizu Wang, Ady Suwardi, Qiang Zhu, Jianwei Xu
Machines all around the world ranging from airline, marine, factories, or even simple smart watches generate heat. More than two-third of energy utilized worldwide is dissipated as heat and released into the atmosphere, so it is important that the waste heat can be utilized to generate eco-friendly power for economic and environmental benefit. Thermoelectric (TE) materials have the ability to convert heat into electricity.1,2 TE generators (TEG) are solid-state semiconductor devices that convert a temperature difference and heat flow into a useful direct current (DC) power source.3,4 TEGs are essentially of solid-state, no movement, and no noise, making them ideal for power generation. with the help of Seebeck effect and Peltier effect, TE materials can generate useful electric (or electromagnetic) fields. in the presence of a temperature gradient, the Seebeck effect develops an electric potential.5 the Peltier effect on the other hand can pass on heat energy against the temperature slope in which a current is driven concurrently against this potential. TE materials enable conversion of electricity into heat pump and vice versa.5–7
2 cycle powered by solar thermal energy
Published in Anoop Kumar Shukla, Onkar Singh, Meeta Sharma, Rakesh Kumar Phanden, J. Paulo Davim, Hybrid Power Cycle Arrangements for Lower Emissions, 2022
Ramneek Singh, Rupinder Pal Singh, Dibakar Rakshit
Waste heat sources are break into three general categories as high grade heat (more than 650ºC), low grade heat (232ºC or lower), and medium/intermediate grade heat (232–650ºC) (Liu, Wang, & Huang 2019; Sajwan, Sharma, & Shukla 2020). Waste heat comes from various industries like petroleum refining, chemical industries, furnaces related to mining and metallurgical industries. Waste heat source may be a stream of hot water or any other fluid-like steam, hot flue gases, cooling unit of compressed export gas. Metallurgical and ceramics industries including glass and brick manufacturers can produce waste heat in the temperature range of 300–400ºC (Sarkar 2015).
Hybrid Energy Systems for Manufacturing Industry
Published in Yatish T. Shah, Hybrid Energy Systems, 2021
Recovering waste heat requires implementation of hybrid process like cogeneration or CHP. Industrial waste heat can be recovered via numerous methods. The heat can either be “reused” within the same process or transferred to another process through process hybridization. Ways of reusing heat locally include using combustion exhaust gases to preheat combustion air or feedwater in industrial boilers. By preheating the feedwater before it enters the boiler, the amount of energy required to heat the water to its final temperature is reduced. Alternately, the heat can be transferred to another process; for example, a heat exchanger could be used to transfer heat from combustion exhaust gases to hot air needed for a drying oven. In this manner, the recovered heat can replace fossil energy that would have otherwise been used in the oven. Such methods for recovering waste heat can help facilities significantly reduce their fossil fuel consumption, as well as reduce associated operating costs and pollutant emissions. As shown below, waste heat can also be converted to power by thermoelectric generator, TPV system, or piezoelectric system. Waste heat (particularly at low temperature) can also be used in heat pump.
Studies on diesel engine exhaust gas for retrieving the waste heat through Triple Tube Heat Exchanger (TTHE) through different tubes
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Mohan Raman, Perumal Saravanan, Suresh Muthusamy, Shankar Subramaniam
The exhaust gas of diesel engine carries about 20%–30% of waste heat. This research is conducted to recover the waste heat from diesel engine exhaust gas via TTHE with various intermediate tubes like corrugated tube, helically finned tube, dimpled tube, protrusion tube and comparing with double pipe heat exchanger, both numerically and experimentally. The TTHE thermal performances and fluid flow characteristics are expressed by the nusselt number, effectiveness, and overall heat transfer coefficient. The recovered waste heat can be utilized for various applications, such as heating, condensing, evaporation processes, boilers, regenerator,and so on. The numerical and experimental analysis has the following conclusions. The effectiveness of TTHE shows around 68% at the end of the full load conditions.The maximum waste heat recovered by using TTHE is around 6.279 KW at full load conditions.If engine life is assumed as 10,000 h, the waste heat recovery TTHE setup has saved around 627,900 kW-Hrs of electricity.Finally, the dimpled tube TTHE has given better performance than other tubes, which is proved by both experimentally and numerically.
Overview of recent developments and the future of organic Rankine cycle applications for exhaust energy recovery in highway truck engines
Published in International Journal of Green Energy, 2020
Julius Thaddaeus, Godwin Unachukwu, Chigbo Mgbemene, Ahmed Mohammed, Apostolos Pesyridis
Increasingly the threat of global warming and associated outcomes are compelling energy planners to focus on developing environmentally friendly energy conversion technologies that produce electricity with fewer emissions. The utilization of waste heat reduces thermal pollutions, mitigates greenhouse gas emissions while fostering energy conservation. The challenges with ORC however are low thermal performance, limited methods to increase work production, the option of working fluids (organic) that suit existing heat sources and sink temperatures and their impact on the environment, (Roy, Mishra, and Misra 2011). ORC is a power cycle which transforms heat to work with ORC fluids. A schematic diagram of a typical organic Rankine cycle that consists of four main components: evaporator, turbine, condenser, and pump is shown in Figure 7 and Figure 8 shows the t-s diagram. As earlier mentioned, ORC is a Rankine cycle, and hence it works on the same operating principle. The liquid is pressurized in the pump (Process 1–2) and then heated and vaporized in the evaporator (by the incoming exhaust gas from the engine in a counter current flow), which causes the fluid to change its state from liquid to vapor (Process 2–3). The now high-temperature, high-pressure vapor is then expanded in the turbine, which extracts energy from the superheated working fluid for mechanical power that generates electricity (Process 3–4). Finally, the vapor upon leaving the expander condenses back to liquid in the condenser (Process 4–1), and the cycle repeats.
A new energy efficient single-stage flash drying system integrated with heat recovery applications in industry
Published in Drying Technology, 2020
The industries are using a tremendous amount of energy described in Figure 1 while some significant amount of energy is wasted in different forms like air streams, flue gases and exhaust gases in the form of heat. Waste heat can be defined as the energy associated with different waste streams of heat like exhaust gases leaving the industry and entering into the environment. These waste heat streams then mix up with atmospheric air and sometimes it causes environmental pollution as well. Even though recovering full available waste heat is not technically feasible, but there is still plenty of room available to improve the efficient use of energy. Greenhouse gases can also be diminished by recovering industrial waste heat.[6] The fundamental source of industrial waste heat is the exhaust gases ejected from heating equipment like boilers and furnaces. These high-grade sources of waste-heat can easily be used for preheating. The results from different studies are extracted in this paper to identify the industrial waste heat sources.[6]