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Abstract A great deal of heat is wasted in intensive public shower facilities, such as those in schools, barracks and natatoriums, which open up at specified time. It will contribute a lot to energy saving and environmental protection with significant economic benefits to recycle the exhaust heat. In this paper, we propose two different kinds of heat pumps (an electric heat pump and an absorption heat pump) in the heat recovery systems. In both system, the used shower water is drained through a pipe and collected in a gray water pool. When the wastewater reaches certain volume, the heat pump system will begin working and recycling heat. The wastewater is filtered and piped to the heat exchanger to exchange heat with the tap water whose temperature will increase from 12 °C to 25 °C with the wastewater temperature dropping from 30 °C to 17 °C. Then the wastewater is piped to the heat pump evaporator and the tap water is piped to the condenser for farther heating. According to the different characteristics of the electric heat pump and absorption heat pump, we also introduce the processes and control methods of different heat recovery systems in details in this paper. Based on a practical example, this paper analyzes and compares the economic and environmental benefits of three retrofitting schemes, including “exhaust heat recovery using electric heat pump”, “exhaust heat recovery using electric heat pump + gas boiler” and “exhaust heat recovery using direct-fired heat pump”. Then we find out that the heat recovery system using direct-fired absorption heat pump has lower energy consumption, less pollution, lower operating cost, and shorter payback period. And it has a promising practical application.

Interconnectivity and interoperability are very important features in the development of integrated energy management systems for industrial facilities. A simple and common strategy for exchanging energy-related information among the entities in a facility is currently lacking. To this end, the purpose of this study is to present an IoT-based communication framework with a common information model to facilitate the development of a demand response (DR) energy management system for industrial customers. Additionally, we developed and implemented an IoT-based energy-management platform based on a common information model and open communication protocols, which takes advantage of integrated energy supply networks to deploy DR energy management in an industrial facility. The experimental results of this study demonstrate that the proposed platform can not only improve the interconnectivity of the entities in industrial energy management systems but also reduce the energy costs of industrial facilities.

Abstract Accurate estimation of the remaining useful life of lithium-ion batteries is critically important for electronic devices. In the existing literature, the widely applied model-based approaches for remaining useful battery life estimation are limited by the complexity of the electrochemical modeling required. In addition, data-driven approaches for remaining useful battery life estimation commonly define unreliable sliding window sizes empirically and the prediction accuracy of these approaches needs to be improved. To address the above issues, use of a hybrid neural network with the false nearest neighbors method is proposed in this paper. First, the false nearest neighbors method is used to calculate the sliding window size required for prediction. Second, a hybrid neural network that combines the advantages of a convolutional neural network with those of long short-term memory is designed for model training and prediction. Remaining useful life prediction experiments for batteries with various rated capacities are performed to verify the effectiveness of the proposed approach, and the results demonstrate that the proposed approach offers wide generality and reduced errors when compared with the other state-of-the-art methods.

Abstract Two office layouts with high and low levels of thermal control were compared, respectively traditional cellular and contemporary open plan offices. The traditional Norwegian practice provided every user with control over a window, blinds, door, and the ability to adjust heating and cooling. Occupants were expected to control their thermal environment to find their own comfort, while air conditioning was operating in the background to ensure the indoor air quality. In contrast, in the British open plan office, limited thermal control was provided through openable windows and blinds only for occupants seated around the perimeter of the building. Centrally operated displacement ventilation was the main thermal control system. Users’ perception of thermal environment was recorded through survey questionnaires, empirical building performance through environmental measurements and thermal control through semi-structured interviews. The Norwegian office had 35% higher user satisfaction and 20% higher user comfort compared to the British open plan office. However, the energy consumption in the British practice was within the benchmark and much lower than the Norwegian office. Overall, a balance between thermal comfort and energy efficiency is required, as either extreme poses difficulties for the other.

Abstract Specification by central government of the heating levels which are to be maintained in British school buildings has recently been altered. This paper is concerned with examining the nature of changes that have been made by comparing present requirements with their counterparts during the preceding one hundred years. Attention is focused on the apparently contradictory implications of these changes for those charged with responsibility for maintaining heating levels in school buildings while, at the same time, conserving fuel. It is suggested that the new statutory requirements present those who are responsible with a duty which may, in practical terms, prove difficult or costly to discharge. Although discussion is specifically restricted to British school buildings, issues are raised which are pertinent to attempts to integrate regulation of heating with control of fuel consumption in other types of non-domestic buildings both in Britain and abroad.

Abstract Hydrothermal treatment (HT) is one of the efficient approaches for upgrading municipal solid waste (MSW). In the present study, emission characteristics of polycyclic aromatic hydrocarbons (PAHs) from hydrothermally treated municipal solid waste (H-MSW) combustion alone and H-MSW/coal co-combustion were investigated at different temperatures. The results showed that for all fuel combustion, the majority of PAHs were 3- or 4-ring PAHs. In addition, flue gas had the highest yields of PAHs followed by fly ash and bottom ash, while the ring number of dominated PAHs in fly ash was higher than those in flue gas and bottom ash. Compared to MSW, H-MSW combustion generated less PAHs at the value of 1131.95–7649.24 μg/g. The blending of H-MSW and coal reduced total PAH emissions and positive interactions were observed between H-MSW and coal during co-combustion. The toxicity equivalent quantity (TEQ) values of the PAHs from combustion were in the order MSW > H-MSW > H-MSW/coal, which was consistent with the total PAH emissions. The present study illustrated that significant reduction of PAH emissions and toxicity from combustion could be achieved by HT and the blending of H-MSW and coal.

It is conventionally believed that there are no self-sustained thermoacoustic oscillations in the absence of acoustic modes in combustors. However, such oscillations (also known as intrinsic thermoacoustic instability) are recently found to occur in a premixed combustor with a mean flow present but no acoustic eigenmodes involved. Practical combustors are associated with entropy waves, pressure jump and mean flow, which are ignored in previous studies without justification. In this work, an entropy-involved energy measure is defined and used to study the stability behaviors of intrinsic thermoacoustic modes. The concepts and methods are exemplified with the classical time-delay n–τ unsteady heat release model. The intrinsic thermoacoustic eigenmodes are found to be related to not only a flame transfer/describing function but also the acoustic impedance at the flame, which is boundary-dependent. It is shown that the predicted frequency ωfr of the intrinsic modes and the critical gain nc depend on the ratio T¯2/T¯1 between the after- and before-combustion temperatures and the inlet mean flow Mach number M¯1. Comparison is then made between the present results and those available in literature. Good agreement is obtained for ωfr. Furthermore, the predicted stability of intrinsic modes based on calculated nc is found to agree well with direct numerical simulations (DNS). It is also interesting to show that as T¯2/T¯1→1, the critical gain as predicted from the previous models is nc→+∞, which means that all intrinsic eigenmodes are stable. However, the present works shows that nc→1.0. Further illustration is then performed by conducting case studies of measured flame transfer and describing functions in premixed combustors. The present work opens up an alternative but more applicable way to study intrinsic thermoacoustic oscillations via the entropy-involved energy measure.

Abstract This paper deals with an optimization of the Stirling engine regenerator’s. Firstly, different materials are experimented (Stainless Steel, Copper, aluminum and Monel 400). The engine performances and the state of each material after 15 h of use are considered. The Stainless steel was the material that best satisfies these two conditions. Five regenerators in stainless steel with different porosities were manufactured and experimented (95%, 90%, 85%, 80% and 75%). Porosity that gives the best trade-off between maximizing the engine brake power, maximizing the heat transfer and minimizing the pressure drops, was retained. Thus, the regenerator in stainless steel with porosity of 85% was considered as the most suitable matrix maximizing the Stirling engine performances and minimizing heat and friction losses.

Abstract This study presents a detailed kinetic investigation into ultra-rich oxidation of H 2 S-CH 4 under high temperature (900–1250 °C) and ambient pressure. Effects of temperature, initial H 2 S/CH 4 ratio and equivalence ratio (Φ) on reactants conversions and products distributions were experimentally studied in a tubular flow reactor and kinetically analyzed by CHEMKIN software. A detailed kinetic mechanism involving 85 species and 515 reactions has been developed and validated using reference data for H 2 S-CH 4 decomposition and results from extended experimental conditions involving the O 2 addition. For H 2 S-CH 4 system, conversion of H 2 S increased steady with the rising temperature while reactivity of CH 4 was weak at temperature below 1000 °C. At temperature higher than 1000 °C, conversion of CH 4 increased rapidly and devoted further formation of H 2 and CS 2 mainly via reacting with H 2 S decomposition products. The H 2 production efficiency was negatively associated with initial H 2 S fraction as H 2 S decomposition was dominant H 2 source within 1150 °C. The stoichiometric ratio for H 2 S/CH 4 merely showed its advantage in H 2 production at higher temperature under which CH 4 reached its equilibrium conversion swiftly. Introduction of little amount of O 2 (Φ = 6 or higher) accelerated the whole reaction process and triggered H 2 S partial oxidation and H 2 formation at lower temperature. CH 4 explicitly showed inferior position in oxidation competition with H 2 S and maintained poor conversion at temperature below 950 °C. The results of rate of production (ROP) analysis at condition without O 2 showed that CH 4 reactivity showed dependence on free S radical via S + CH 4 = SH + CH 3 , and the formed CH 3 was mainly converted via reacting with SH and H radicals. CH 3 could be concurrently reverted to CH 4 via reactions with H 2 S and H 2 . O 2 activated the whole system by forming chain branching radicals O and OH. These radicals promoted H 2 S and CH 4 conversions to form richer S, H and CH 3 radicals. SH + CS = CS 2 + H was important for CS 2 formation and with presence of O 2 , CS 2 was likely to be consumed via oxidation reactions. Finally reaction pathways for H 2 S, CH 4 conversion and H 2 , CS 2 formation were presented.