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In this paper, a numerical study is carried out to investigate the performance of a coupled BIPV/T-AHU system in Sudan. A mathematical model was utilized, Matlab Simulink was used to do simulation. Results showed good agreement with experimental data from the literature. The problem studied in this paper is reducing the energy required for heating in winter (preheating BIPV/T) and avoiding the high photovoltaic cell temperature in summer. We compare the energy consumption with and without BIPV/T-AHU in different cities in Sudan. The results showed that utilizing the exhaust air to cool the photovoltaic cell could reduce the PV/T cell temperature in the range (9−12)∘C, which can increase the electrical power output in a range of (12−21.44)W/m2. In winter, utilization of the preheating BIPV/T system can decrease the heating load in Wadi Halfa in the range of (6−107.1%). Damazein does not need a high heating power in the daytime for the air conditioning system depending on the local climate, so the heat energy produced by the system can be used for drying, desiccant cooling, or heating water, with increasing the electric power produced by cooling PV/T cells. The results indicated a great possibility to use the BIPV / T system under the studied conditions, in addition, this study provides important information for the application of the BIPV / T system in these areas.

Research on the window operating behavior of offices is of great significance for reducing building energy consumption and improving indoor comfort. The open-plan office is a common office form that involves a large number of people and a complex staff composition. The window operating behaviors in open-plan offices are also random and various. This study took three open-plan offices with different situations (area, office type, staff composition, etc.) as an example, which provides a new perspective on how people behave differently when opening or closing windows. The window operating behaviors in two typical seasons (summer and transition seasons) were recorded and analyzed. The occupants’ schedules and influencing factors of window operating behavior were investigated by questionnaire surveys. In addition, the indoor environmental parameters, occupancy situation, and on-off statuses of windows and air conditioning were acquired through field measurements. Furthermore, the differences in window operating behaviors in the three open-plan offices were compared from the perspectives of influencing factors, duration of the window on-off statuses, and cause of window control actions, among others. In addition, Spearman Correlation Coefficient was used to analyze the ranks of the candidate motivations for window operating behaviors. The preliminary results show that influenced by the personnel composition, type of air conditioner and adjustable degree of windows, the window operating behaviors of different office buildings have larger discrepancies than that in the same building. However, there were some common characteristics in the window regulation behaviors of the three open-plan offices: they were generally influenced by the coupling of environmental factors, schedule factors, and equipment factors. This study reveals that when expand the research object from a single building to multiple buildings, more difficulties and challenges would be involved into behavior research.

Due to the fluctuation and intermittency of distributed PV generation, battery energy storage is required with higher renewable installation towards carbon neutrality. Thus, the photovoltaic battery (PVB) system receives increasing attention. This study provides a critical review on PVB system design optimization, including system component sizing and strategy improvement studies, from mathematical modeling, evaluation system establishment to feasibility and optimization studies. Several PVB simulation software packages are compared and evaluated, and acknowledged system models are presented. The evaluation indicators are summarized from various aspects with cases of various evaluation systems combining different indicators or using the Pareto front for multi-criteria system designing. The PVB system feasibility study is analyzed from system configuration variation, critical technical and economic parameter analyses, rule-based operation strategies to future expectations like large-scale energy storage profitability, grid parity, and energy community trading platform. The targets, methods, tariff and time resolution influences, and PVB system capacity optimization design recommendations are critically discussed. The research directions for system operation development and future expectations are analyzed from system feasibility, flexibility to resilience. The co-planning of PVB system capacity and operation design optimization makes the problem complicated, leading to relatively short time resolution but more flexibility to system operation strategy. This study could provide guidance and references to distributed PVB system future design and optimization studies.

The restructuring of the energy industry is imperative, as New Zealand strives to reduce greenhouse gas emissions. New Zealand has abundant renewable energy resources, and about 85% of current electricity generation is from renewable energy sources. However, in recent years, it appears that a considerable fraction of wind energy has been underutilized. This article reviews the history, current status, and future trends of wind energy development in New Zealand. The main challenges to the current development of wind energy are summarized compared to other countries. The main challenges come from the bi-cultural influence, environmental influence, and economic and social influence due to the variable nature of wind power, it is critical to store and operate power safely and reliably during peak power generation periods. This article compares seven mainstream wind energy storage technologies and analyzes the best solution for wind energy storage in New Zealand. This article analyzes the feasibility of using small-scale household (standard power rating range from 0.004 to 16 kW) wind turbines in New Zealand cities regarding their construction and operation process. The life cycle and the maximum capacity coefficient of such small-scale wind turbines are overviewed via three case studies and later compared with large commercial wind turbines (standard power rating ranges from 1 to 3 MW) in power generation capacity. It has been found that small-scale household wind turbines have notable power generation potential and economic benefits in the long term.

Under the dual effects of aerodynamic heating and high-power electronic equipment heating, the heat sink and power demand of advanced high-speed aircraft have been exponentially rising, which seriously restricts the aircraft performance. To improve system cooling and power supply performance and reduce engine performance loss, a power and thermal management system (PTMS) with high performance, low energy consumption, and light weight urgently needs to be developed. In this paper, three modes of a potential PTMS with different heat sinks and bleed air sources are further discussed to analyze and compare the optimal matching with the flight mission at Mach 1–4.4. The equivalent mass method is used to uniformly assess the costs of the fixed weight, bleed, resistance, etc. as a function of the fuel weight penalty, which is chosen as the optimization objective. The optimization variables consist of the compressor outlet temperature, cooling air flow rate, and fan duct heat exchanger structure size. The results show that the intermediate-stage bleed air and fan duct heat sink are more suitable when the Mach number is less than 2, but the ram air bleed is highly suitable for flight missions at a high Mach number. Especially at Mach 3.4–4.4, the ram air bleed mode can respond to the cooling and power demands with a simple architecture.

The cogeneration system of heat, power, and biogas (CHPB) driven by renewable energy provides an effective solution for carbon emission reduction in rural China. Starting from fully meeting the energy demand of 17 new rural residential households in Lanzhou, considering the annual dynamic local climate change, energy consumption characteristics, and environment parameters, a model of environmental benefit index for the CHPB system is constructed. The concept of emission factor is used to quantitatively analyze the environmental benefits of the system. The equivalent CO2 emission factor is defined to connect emissions with energy output, evaluating the environment-friendly potential of energy supply system. Compared with the conventional systems of independent power and thermal generation, the year-round characteristics of CO2 emission and emission structure chart of the proposed system are analyzed. The results show that the total CO2 emission and the average equivalent CO2 emission factors of the conventional and CHPB system are 85.45t, 1.53 kg/kWh, and 308.46t, 0.22 kg/kWh, respectively. The maximum CO2 emission reduction ratio of the CHPB system is 113.47%. Anaerobic digestion technology is employed to consume biomass feedstock, which reduced CH4 emission (equivalent to 86.36t of CO2 emission reduction). Five typical cities were selected to study the regional adaptability of the system and analyze environmental benefits. The results indicate that the CHPB system has the best environmental performance in Guangzhou, where the average CO2 emission reduction rate is 103.52%.

Variable air volume air-conditioning system (VAV system) has multiple control loops that interfered with each other, which has serious impacts on its actual operation effect. To solve this problem, the index of global hydraulic stability, which takes the physical quantity of the pipe network pressure and the air flow rate as reference, is proposed based on Graph theory, and a pipe network model for the hydraulic calculation is built. Then, the simulation study based on the actual operation data is carried out in MATLAB. The distribution of the pressure and the air flow in the pipe network is obtained, and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy (DP strategy) and fan frequency regulation strategy (FF strategy). Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy, and then the fluctuation of the pressure and the air flow can be reduced. The contribution of this study is to provide an evaluation index of global hydraulic stability, which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.

Renewable energy technologies, particularly in electric vehicles (EVs), have received significant attention in recent years. The wasted energy in a vehicle's shock absorber can be converted into an alternative energy source by regenerative shock absorbers. In this paper, a high-efficiency regenerative shock absorber considering twin ball screws transmissions is proposed for application in range-extended electric vehicles. The proposed regenerative shock absorber can convert vibrational kinetic energy, which is traditionally dissipated as heat in suspension systems, into electricity. The proposed system is divided into four modules: suspension vibration input module, transmission module, generator module and power storage module. Induced by road roughness, the irregular linear oscillations of the suspension are transmitted to the suspension vibration input module. The reciprocating vibrations are converted into unidirectional rotation of the generator by a pair of ball screws, gears, and two overrun clutches in the transmission module. The utilisation of different screw pitches leads to different damping coefficients for upward and downward progress, enabling the shock absorber to fully utilise elastic elements to improve vehicle comfort when compressed and quickly absorb vibrations when stretched. The electricity produced by the generator is stored in supercapacitors to charge the battery and extend the range of EVs. The mechanical properties of the full-scaled fabricated prototype were studied by utilising a mechanical testing and sensing fixture. An average power output of 3.701 W in 1Hz-3 mm sinusoidal vibration input and a peak efficiency of 51.1% and average efficiency of 36.4% were achieved in a bench tests. The range can be approximately extended by 1 mile per 100 miles when EV is driving on the road of class B with a speed of 60 km/h, demonstrating that the proposed high-efficiency regenerative shock absorber is beneficial for harvesting renewable energy, and practical and significant for extending the range of EVs.