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Low-energy approaches for the thermal control of buildings
Published in Paul Tymkow, Savvas Tassou, Maria Kolokotroni, Hussam Jouhara, Building Services Design for Energy-Efficient Buildings, 2020
Paul Tymkow, Savvas Tassou, Maria Kolokotroni, Hussam Jouhara
In this chapter we have considered a number of approaches that can be employed in isolation or in combination with traditional technologies to satisfy the heating and cooling requirements of commercial buildings. One such low-energy technology that can be employed to provide both heating and cooling is the heat pump. Heat pumps remove thermal energy from a low-temperature source and supply it to a higher temperature sink. In recent years the ground has become a popular energy source for space heating, as well as a sink for heat rejection, due to its relative constant temperature throughout the year. Heat pumps can also be used to recover and upgrade heat from the exhaust air from buildings. Other thermal energy recovery systems include fixed plate and rotary heat exchangers, run-around coils and heat pipes.
Environmental Life Cycle Assessment and Regulatory Issues of Innovative Green Extraction Procedures
Published in Francisco J. Barba, Elena Roselló-Soto, Mladen Brnčić, Jose M. Lorenzo, Green Extraction and Valorization of By-Products from Food Processing, 2019
Erasmo Cadena, Mathilde Fiorletta
Including environmental considerations in processes design, control, and optimization is nowadays a real topic of interest, as well as a necessity. Most of the extraction technologies that have emerged during the last few years are known as green extraction processes. Microwave-, ultrasound-, pulsed electric field (PEF)-assisted extractions, and extractions using pressurized fluids can be found among them. The concept of Green Chemistry promotes six specific principles for the extraction of natural products (Herrero & Ibañez, 2018): (i) selection of renewable plant resources; (ii) use of alternative solvents and water or agro-solvents; (iii) reduction of energy consumption by energy recovery and using innovative technologies; (iv) production of coproducts instead of waste to include the bio- and agro-refining industry; (v) reduction of unit operations and favor safe, robust, and controlled processes; and (vi) aim for a non-denatured and biodegradable extract without contaminants.
Technical and Economic Assessment of Biogas and Liquid Energy Systems from Sewage Sludge and Industrial Waste
Published in Vladimir Strezov, Hossain M. Anawar, Renewable Energy Systems from Biomass, 2018
Hossain M. Anawar, Vladimir Strezov
Different technologies have been developed to treat the wastewater and recover the renewable energy, such as biogas, bioethanol, and heat (Stafford et al., 2013). Based on the current data analysis, the estimates showed that 3,200–9,000 MWth of energy might be recovered from wastewater generated from livestock and industrial and domestic wastewater in South Africa. Besides energy recovery, the additional economic and environmental benefits may include reduction in pollution, water reclamation, reduced carbon footprint, and nutrient and material recovery. Various technological options involving energy recovery from wastewater include three steps, in which the inputs are converted into intermediates and then intermediates are converted into energy outputs.
Membrane desalination of ballast water using thermoelectric energy from waste heat
Published in Journal of Marine Engineering & Technology, 2022
Ballast water management and treatment is an important part of the economic portfolio for marine industry operations (Balaji and Yaakob 2012). Increasing environmental awareness and stringent environmental regulations call for proper treatment and disposal of ballast water. Among the many environmental concerns associated with marine industry operations, environmental emissions and pollution footprint from fossil fuel consumption is a very critical concern. About 50% of fuel input supplied to marine engines results in waste heat through various forms such as main engine exhaust, scavenger air cooling, and other water cooling streams (Biswas et al. 2018). To improve energy efficiency, various approaches including waste heat recovery systems have been considered (Kristiansen et al. 2012; Suárez de la Fuente and Greig 2015; El Geneidy et al. 2018). Energy recovery systems to extract energy from waste heat sources include energy storage units, thermoelectric generation units, energy recycling through various recovery streams.
An Investigation into the Thermal Boundary Resistance Associated with the Twin Boundary in Bismuth Telluride
Published in Nanoscale and Microscale Thermophysical Engineering, 2019
Due to the energy crisis and the environmental protection issue, there has been a high demand for alternative energy and waste-energy recovery in recent decades. One of the potential technologies for waste-energy recovery is a use of the thermoelectric (TE) devices which can convert heat directly into electricity. Modern TE devices, however, have very limited efficiency because of the strict requirements of materials that must be a good electrical conductor with a large TE conversion coefficient but at the same time a poor thermal conductor. The performance of TE materials is characterized by the dimensionless figure-of-merit zT, where S, σ, and T are the Seebeck coefficient, electrical conductivity, and temperature (K); kl and ke are the lattice and electronic thermal conductivities, respectively. The larger the zT, the higher the efficiency is. According to the principle of phonon glass electron crystal, an ideal TE material should conduct electricity as well as crystalline conductors, and conduct heat as poorly as glasses [1].
Energy efficiency of hydraulic regenerative braking for an automobile hydraulic hybrid propulsion method
Published in International Journal of Green Energy, 2019
Wei Wu, Hui Liu, Junjie Zhou, Jibin Hu, Shihua Yuan
The detailed energy distributions under three different conditions in the UDDS cycle are given in Figure 10. The driving parameters are presented in Table 4. Erl is the energy loss caused by the rolling resistance. Eal is the energy loss caused by the air resistance. Ehl is the energy loss caused by the hydraulic system. The energy loss caused by the rolling resistance is mainly determined by the driving distance during braking. The air resistance energy loss is mainly related to the driving distance and the speed. The energy loss caused by the hydraulic system varies under different conditions. In the regenerative braking condition 1, the vehicle speed changes from 11.7 m/s to 0 m/s in 9.7 s. The vehicle speed changes from 11.8 m/s to 8.6 m/s in the condition 2 in 3.7 s. The energy losses caused by the hydraulic system in the condition 1 increases slightly with a high pressure compared with the condition 2. However, the energy loss of the rolling resistance is reduced due to a shorter driving distance. A higher energy recovery rate is also achieved. In the condition 3, the vehicle speed changes from 12.4 m/s to 11.2 m/s in 2.7 s. The vehicle speed changes little and is higher than the other two conditions. The higher HT and hydraulic motor speeds under a higher vehicle speed enlarge the frictional loss. It seems that the proportions of the rolling resistance energy loss and the air resistance energy loss become higher when the average vehicle speed becomes larger during braking. The proportion of the energy loss caused by the hydraulic system also becomes larger and obvious. The proportion of energy recovered becomes small.