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A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet) and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.

Managing thermal comfort, in both hot and cold climates, critically influences energy use in homes [1-4]. For low income households, who commonly live in thermally poor housing stock, maintaining thermal comfort can be costly relative to household income, leading to trade-offs between comfort, energy use and affordability. Comfort as a concept has been explored from many vantages, including as a physiological need [5,6]; a parameter for healthy housing [7]; as an energy efficiency building standard [4,8] and a cultural construct [9,10]. Yet, there is little research available that provides detailed insight into the relationship between thermal comfort and energy efficiency in existing housing stock or about the impact of support programs on these key indicators. This paper reviews measures of household thermal comfort as they relate to energy efficiency assessments in a project, Get Bill Smart (GBS), that worked with low income households in Tasmania, Australia. Thermal comfort and energy use data was collected over 15 months from 51 households, a sub-set of the 510 households participating overall. Longitudinal interviews and housing observations were also conducted. New thermal comfort and energy efficiency indicators were developed from this data. This paper demonstrates the application of these indicators by providing examples of findings in GBS. Suggestions are made for the refinement of measures discussed for use in future applications.

To integrate more renewable energy into the power grid, large-scale thermal power plants have to extend their operating ranges and participating in deep peak shaving. In order to improve the thermal economy of large-scale thermal power plants participating in deep peak shaving, and to determine the performance of a thermal system under different conditions, a method of modeling for the performance prediction of large-scale thermal power plants in deep peak shaving is proposed. In the algorithm design of the model, a three-layer iterative cycle logic is constructed, and the coupling relationship between the parameters of the thermal system is analyzed from the mechanism level. All of the steam water parameters and the correction values of the flow rate at all levels of the system after the parameter disturbance are obtained. The algorithm can simulate the response of a thermal power plant under load variation and operation parameter variation. Compare the error between the data given by the prediction model and the test, the accuracy of the proposed prediction model is verified. When the unit participates in deep peak shaving, the prediction model is used to analyze the relative deviation of the unit thermal efficiency caused by cycle parameters and energy efficiency of equipment. It provides a date basis for the performance evaluation and multi-parameter coupling optimization. The research results can be used to determine the operation mode and equipment transformation scheme.

[EN]In order to utilize the low-grade thermal energy efficiently, a more realistic model of thermally regenerative electrochemical cycles system with continuous power output is proposed in which the heat transfer irreversibility, external heat leakage and non-ideal regeneration losses are taken into account. Besides, the symmetry of cells, which is necessary for a practical thermally regenerative electrochemical cycles system operated at steady state, is considered. Analytic expressions for the efficiency and power output of the system are derived. The design and operation criteria of the system for achieving continuous power output are obtained. The general performance characteristics and the optimally operating regions of several parameters are reported. The influences of the external heat leakage on the system performance and the upper and lower bounds of efficiency at maximum power output at different situations are evaluated and discussed. National Natural Science Foundation of China (No. 11405032) and Junta de Castilla y Leon under project SA017P17. Universidad de Salamanca contract 2017/X005/1.

This paper presents the performance evaluation of an integrated photovoltaic thermal (PVT) collector-phased change material (PCM) thermal energy storage (TES) system. The PVT collectors can generate both electricity and low-grade thermal energy during the daytime, and the thermal energy generated can be temporarily stored in the PCM TES unit and used for space heating during the night-time. Taguchi method and analysis of variance are used for the simulation design and data analysis, respectively. The thermal performance of the proposed system was evaluated in terms of the useful energy stored in the TES system. The results showed that the outlet air temperature of the TES unit remained at least 2°C higher than the inlet air temperature during the discharging process in the selected test day. The PCM type and the PCM charging air flow rate were the most important factors influencing the useful energy stored in the TES system.

This study selects five parameters as decision variables for the optimization design of an ocean thermal energy conversion system, including the evaporating temperature, the condensing temperature, the pinch-point temperature difference between the evaporator and condenser, and the working fluid flow rate. The optimization goal is to maximize the net output power per unit area and the exergy efficiency. The final scheme is comprehensively screened out from the Pareto solution set through some evaluation indexes. Finally, this study also analyzes the effects of four decision variables on the optimization objectives and the evaluation indexes. This study finds that evaporating temperature and condensing temperature have similar effects on the two objective functions. However, the pinch-point temperature difference has different effects on them. The back work ratio is obviously affected by the condensing temperature. A small pinch-point temperature difference is beneficial and improves the performance of an ocean thermal energy conversion system. The effects of evaporating temperature and condensing temperature on the investment cost per unit net output power are roughly similar to those on the net output power per unit heat exchange area. However, the effects of the pinch-point temperature difference on the two performance aspects are inconsistent.

作为中国37处世界遗产之一，“福建土楼”具有杰出的历史价值。而其适宜的人居生态环境，一直以来也为国内外学者所称道。南靖土楼营造出了符合人体热舒适要求的建筑空间。兴建土楼的工匠们通过了大量又朴素的建筑实践，探索出了许多被动式建筑节能的技术。可是，人们对于土楼的节能技术的研究，长期以来一直停留在定性的阶段。 本文以南靖土楼为研究对象，通过实地测试，对比分析、定量分析等途径，对南靖土楼的热环境、能耗情况等方面问题作了一定深度的探讨。 论文研究方法有调研法、问卷法、归纳法、测试法、模拟法等。通过调研获得南靖土楼的相关资料；通过土楼居民及游人热舒适感受的问卷调查，结合科学的模糊评价方法，来对土楼的热. ; As one of China's 37 world heritages, "Fujian Earth Building" Nanjing section has an outstanding historical value. Its suitable ecological environment for people living has been praiseworthy by domestic and foreign scholars. Nanjing earth Buildings has created the thermal comfortable architecture space which can meet our body needs. The earth building artisans ns through the practice of simple con. ; 学位：工学硕士 ; 院系专业：建筑与土木工程学院建筑系_建筑技术科学 ; 学号：25220071151323

The thermal performance of buildings in the south of China focuses on thermal mass design, while in the north it favors thermal insulation design, which makes it impossible to achieve a balance between the thermal mass and insulation. Here, a comprehensive evaluation index is developed to measure the thermal performance of a building’s external envelope, which aims to find out the optimal range of the wall thickness under the influence of the thermal mass and insulation, and to seek the correct balance between a building’s energy consumption and the thermal performance of walls. In this paper, four dimensions, namely the heat transfer coefficient, thermal inertia index, attenuation degree, and delay time, are discussed, and the weight coefficients of each subfactor are calculated and isotropically treated to create comprehensive evaluation indicators. Then the distribution laws of the composite index values of common building materials in different climatic zones are examined. The result shows that the correlation coefficient (R2) between M and building energy consumption is about 0.7736–0.8215, which is higher than 0.3494–0.384, the heat transfer coefficient, and is more accurate in predicting building energy demands. Furthermore, through the analysis of the thermal improvement rate and the building energy-saving rate, the suitable wall thickness of commonly used building materials in different climate zones is determined, and the application prospects of the research results are described. With the above research findings, the thickness ranges of walls can be determined at the initial period of building design by combining regional environmental factors and material characteristics to provide a reference for building energy-saving design.