Search Results (27)

The combined cooling, heating, and power system is based on the principle of energy cascade utilization, which is conducive to reducing fossil energy consumption and improving the comprehensive utilization efficiency of energy. With the characteristics of a lower expansion ratio and larger recuperation of a supercritical carbon dioxide (SCO₂) power cycle, a combined cooling, heating, and power (CCHP) system is proposed. The system is based on a SCO₂ cycle and is driven by solar energy. The system is located in Qingdao and simulated by MATLAB/Simulink software (R2022b). Firstly, the thermodynamic performance of the CCHP system at the design condition is analyzed. The energy utilization efficiency of the CCHP system is 79.75%, and the exergy efficiency is 58.63%. Then, the thermodynamic, environmental, and economic performance analyses of the system under variable conditions are carried out. Finally, the solar multiple is optimized. The results show that the minimum levelized cost of electricity is 10.4 ¢/(kW·h), while the solar multiple is 4.8. The annual primary energy saving rate of the CCHP system is 85.04%, and the pollutant emission reduction rate is 86.05%, compared with the reference system. Therefore, an effective way to reduce environmental pollution and improve the utilization efficiency of solar energy is provided. Full article

The residential sector accounts for over a third of the world’s energy use. Even though this ratio is lower in Mexico, there is a pressing housing deficit, especially regarding low-cost homes. This research aimed to create a reference building (RB) to understand the current energy consumption of multi-family buildings across different climatic zones. The aim was to assess their energy performance and promote reduced energy requirements as a guideline for designing and constructing affordable, low-energy, or zero-energy buildings. The present work conducts a diagnosis of the current energy consumption of multi-family buildings in eight cities in Mexico. First, a reference building was developed to represent typical Mexican building geometry and construction practices, and then the building’s fixed and variable energy requirements were simulated. Finally, a comparison was made between the energy requirement and the data reported by the national energy survey. Therefore, it was possible to generate a reference building from national data sources complying with national regulations, where materials, occupant behavior, and equipment were chosen to help represent the building’s thermal behavior. Domestic water heating was identified as a driver of variable energy requirements in all cities. In contrast, the simulated heating and cooling requirements were directly linked to the city’s climate. Electricity bills tended to mostly correspond with the results that excluded the use of heating systems. Lastly, while comparing LPG (Liquified Petroleum Gas) consumption was challenging due to the unavailability of national data, LPG requirements were closely estimated for temperate cities. The definition of a reference building is an important step towards developing nZEB in Mexico, as these buildings are valuable tools that can contribute to the energy evaluation of specific types of buildings. This characteristic makes them convenient for revising a building code or setting new national energy policy goals. Full article

Air conditioning is vital for indoor comfort but traditionally relies on vapor compression systems, which raise electricity demand and carbon emissions. This study presents a novel thermo-mechanical vapor compression system that integrates an ejector with a conventional vapor compression cycle, incorporating a thermally driven second-stage compressor powered by solar energy. The goal is to reduce electricity consumption and enhance sustainability by leveraging renewable energy. A MATLAB^® model was developed to analyze the energy and exergy performance using R1234yf refrigerant under steady-state conditions. This study compares four solar collectors—evacuated flat plate (EFPC), evacuated tube (ETC), basic flat plate (FPC), and compound parabolic (CPC) collectors—to identify the optimal configuration based on the collector area and costs. The results show a 31% reduction in mechanical compressor energy use and up to a 44% improvement in the coefficient of performance (COP) compared to conventional systems, with a condenser temperature of 65 °C, a thermal compression ratio of 0.8, and a heat source temperature of 150 °C. The evacuated flat plate collectors performed best, requiring 2 m²/kW of cooling capacity with a maximum exergy efficiency of 15% at 170 °C, while compound parabolic collectors offered the lowest initial costs. Overall, the proposed system shows significant potential for reducing energy costs and carbon emissions, particularly in hot climates. Full article

The design of a high energy performance building requires an assessment of the various design options. Energy simulation offers interesting possibilities for clarifying the architect’s decisions at this level, especially in the initial design phases where the greatest opportunities for optimization lie. The aim of this work is to develop an approach for the evaluation and optimal use of energy simulation in the building design phases. To do this, EnergyPlus building simulation software was used to simulate the energy consumption of the Faculty of Electrical Engineering building at “Gheorghe Asachi” Technical University in Iasi, in order to identify the factors influencing energy consumption in buildings. The results of this study show that an increase in the cooling setpoint temperature from 22 °C to 28 °C in the roof construction can reduce operating temperatures by 14.2% and 20.0%, respectively. This optimization could significantly reduce the hours of thermal discomfort, in a ratio of 6.0 and 3.25, respectively. Consequently, optimizing parameters linked to design and the heating and cooling systems within the building makes it possible to achieve energy savings and ensure thermal comfort in buildings. Full article

In this study, an energy management model for electric vehicles including the entire vehicle such as the cabin, electric motors, battery, and the heating–cooling system was prepared. The heating and cooling processes for electric vehicles were run according to the internationally recognized driving cycles as well as at constant speeds to investigate them under different ambient conditions. The heating–cooling processes were managed in line with the cabin temperature target determined by considering the comfort conditions. The energy consumption of each of the system elements and the system in the heating–cooling process in electric vehicles was analyzed. Under different operating conditions, the variation of cabin temperature with time, instantaneous power, and cumulative energy consumption was calculated. The effect of heating and cooling processes on energy consumption, charging rate, and range were analyzed and interpreted. The results showed that the heating–cooling system for the heating process consumed more energy when the ambient temperature decreased, and the charge consumption ratio as well as the range deformation rate increased to about 30% when the ambient temperature was –10 °C. Similarly, the heating–cooling system for the cooling process consumed more energy when the ambient temperature increased, and the charge consumption ratio as well as the range deformation rate reached up to 40% when the ambient temperature was 40 °C. When the outdoor conditions were close to the thermal comfort temperature of 23 °C inside the cabin, the total energy consumption and the range deformation rates were reduced to less than 10%. Full article

Building operations account for a large amount of energy use and CO₂ emissions, and the morphology of buildings in residential clusters strongly impacts energy efficiency performance. However, little research has focused on the morphology and energy electricity usage of high-rise residential clusters in hot summer and cold winter (HSCW) regions. We investigated 96 residential clusters in Hangzhou, China, and established a corresponding morphology database. Additionally, we obtained annual electricity consumption for 16 of these residential clusters. With this database, we performed optimization of morphological parameters upon energy use intensity (EUI) using a genetic algorithm (GA). Specifically, the cooling, heating, and lighting EUIs of high-rise residential clusters were studied. After implementing the optimized morphological parameters, there was a reduction of up to 7.73% in EUI. According to regression analysis, the average aspect ratio was the most significant factor influencing EUI (r = −0.907), followed by floor area ratio (r = −0.755), average orientation (r = 0.502), and average number of floors (r = −0.453). These results indicate that a higher intensity of land development with a greater floor area ratio, average aspect ratio, and average number of floors can reduce total energy consumption. Additionally, we found that an average building orientation of southwest 15° (with respect to south) is optimal. The findings of this study can assist urban planners and designers in developing more sustainable residential clusters, leading to decreased energy costs and CO₂ emissions. Full article

Shallow geothermal or ground source heat pump (GSHP) energy systems offer efficient space heating and cooling, reducing greenhouse gas emissions and electrical consumption. Incorporating ground heat exchangers (GHEs) within pile foundations, as part of these GSHP systems, has gained significant attention as it can reduce capital costs. The design and optimisation of GHEs connected in parallel within energy piles have been researched widely, considering symmetrical placement, while the potential misplacement due to construction errors and the optimal placement remain mostly unexplored. This study utilises 3D finite element numerical methods, analysing energy piles with diameters from 0.5 m to 1.4 m, equipped with parallelly connected U-tube and W-tube GHEs. The impact of GHE loop placement is analysed, considering the influence of the ground and concrete thermal conductivities, pile length, fluid flow rate, GHE pipe diameter, and pile spacing. Results indicate a marginal impact, less than 3%, on the overall heat transfer when loops deviate from symmetry and less than 5% on the total heat transfer shared by each loop, except for highly non-symmetric configurations. Symmetrical and evenly spaced loop placement generally maintains favourable thermal performance and ease of installation. This study underscores the flexibility in GHE design and construction with a low risk of thermal yield variations due to uncertainties, particularly with a separation-to-shank distance ratio between 0.5 and 1.5 in a symmetrical distribution. Full article

Building energy consumption is the main urban energy consumption component, which mainly serves people-centered work and living energy demands. Based on the physical requirements of humans in urban buildings and to determine the comfortable body temperature in each season, this paper establishes a sizing optimization model of building-type integrated energy systems (IES) for sustainable development, where the cooling and heating loads required to maintain indoor somatosensory body comfort temperature are calculated. Depending on the external energy price, internal power balance, and other constraints, the model develops an optimal sizing and capacity-planning method of energy conversion and storage unit in a building-type IES with PV generation. The operating principle is described as follows: the PV generation is fully consumed, a gas engine satisfies the electric and thermal base load requirements, and the power system and a heat pump supply the remaining loads. The gas price, peak-valley electricity price gap, and heat-to-power ratio of gas engines are considered important factors for the overall techno-economic analysis. The developed method is applied to optimize the economic performance of building-type IES and verified by practical examples. The results show that using the complementary characteristics of different energy conversion units is important to the overall IES cost. A 300 kW building photovoltaic system can reduce the gas engine capacity from 936.7 kW to 854.7 kW, and the annual cost can be approximately reduced from 7.82 million to 7.50 million RMB yuan. Full article

This study investigated the economic feasibility of introducing a new energy system, the greenhouse–fuel cell convergence system (GFCS), to a greenhouse that consumes a lot of energy. The GFCS is a concept that uses the heat generated during the power generation process to cool and heat the greenhouse, uses the emitted CO₂ as fertilizer inside the greenhouse, and sells the generated electricity. For economic evaluation, the annual energy consumption of the greenhouse was first calculated through simulation, and then the appropriate fuel cell capacity was determined. Next, a farmer-led business model and a utility-led business model were presented, and the economic feasibility of these models was evaluated for tomatoes and mangoes. The economic evaluation of the GFCS confirmed the economic feasibility by comparing it with a greenhouse equipped with a geothermal heat pump. The results of the economic evaluation revealed that the farmer-led model had a benefit–cost ratio (B/C) ranging from 0.62 to 0.65 even with government support for heat utilization facilities, which was lower than that of a typical greenhouse (1.03 to 1.06). On the other hand, the utility-led model showed high B/C ranging from 1.19 to 1.86. If the initial investment cost of the fuel cells is reduced and a government policy is appropriately supported, the GFCS can be economically applied to greenhouses. Full article

Air conditioning has become a necessity in people’s daily life. The performance of the compressor determines the energy efficiency ratio of this electrical equipment, but the heat generated during the operation of its internal core power components will greatly limit its performance release, so it is urgent to carry out research on the heat dissipation of power devices. In this work, we explore the application of thermoelectric coolers (TECs) in the field of power device heat dissipation through finite element simulation. First, we geometrically modeled the structure and typical operating conditions of core power devices in air conditioners. We compared the temperature fields in air-cooling and TEC active cooling modes for high-power-consumption power devices in a 319 K operating environment. The simulation results show that in the single air-cooling mode, the maximum temperature of the 173.8 W power device reached 394.4 K, and the average temperature reached 373.9 K, which exceeds its rated operating temperature of 368.1 K. However, the maximum and average temperature of the power device dropped to 331.8 K and 326.5 K, respectively, at an operating current of 7.5 A after adding TECs, which indicates that TEC active cooling has a significant effect on the temperature control of the power device. Furthermore, we studied the effect of the TEC working current on the temperature control effect of power devices to better understand the reliability of the TECs. The results show that TECs have a minimum working current of 5 A, which means it has no significant cooling effect when the working current is less than 5 A, and when increasing the current to 10 A, the average temperature of the power device can be reduced to 292.9 K. This study provides a meaningful exploration of the application of TECs in chip temperature control and heat dissipation, providing a new solution for chip thermal management and accurate temperature control. Full article

The present study provides comprehensive analyses of a newly constructed passive energy-efficient building located in Harbin, China, which is a prime example of how to design a passive building that withstands the severe cold climate in northeast Asia. Conduction transfer functions of heat flux equilibrium are employed to simulate energy consumption characteristics of the paradigm passive building. The climatic conditions in severe cold region are analyzed, and the energy-saving designs in the studied engineering cases are summarized for their practical applications. Building physical models are established to perform numerical simulation analyses on the passive building paradigm in northeast Asian frigid zone. The dominant technical parameters of envelope structure affecting energy consumption in severe cold region, including thermal insulation thickness and heat transfer coefficient of building envelope, as well as window-to-wall ratio for each building facade, are taken into consideration as simulation variables to calculate cooling load, heating load, electricity consumption, and CO₂ emission, which account for energy efficiency of passive buildings. The simulation results demonstrate the high energy-saving potential of the proposed passive building design and render the optimal energy-efficient parameters suitable for severe cold regions, which can reduce energy consumption and CO₂ emission while ensuring comfort for occupants. The present study provides a theoretical reference for envelope structures of passive buildings in severe cold regions, which is of great significance to the development of green buildings and relevant policies. Full article

Environment control systems in broiler houses utilize non-renewable electricity and fuels as energy sources, contributing to the increase in greenhouse gases, while not providing optimal conditions. The heat pump (HP) is an energy-efficient technology that can continuously regulate the indoor temperature and relative humidity by combining different operation modes (heating, cooling, and dehumidifying). The current study presents an analytical numerical model developed in Simulink, capable of simulating the thermal loads of a broiler house and the dynamic operation of three heat pumps to cover its needs. Outdoor climatic conditions and broilers’ heat production are used as inputs, while all the heat exchange mechanisms with the external environment are considered. The study investigates the energy use and performance of each HP mode under different environmental conditions. A total of 7 different production periods (PPs) are simulated for a 10,000-broiler house in northern Greece, showing total energy consumption of 18.5 kWh/m², 43.4 kWh/m², and 58.7 kWh/m² for heating, cooling, and dehumidifying, respectively. The seasonal coefficient of performance (SCOP) reaches above 3.1 and 4.8 for heating and dehumidifying, respectively, while the seasonal energy efficiency ratio (SEER) for cooling is above 3.7. Finally, focusing on the two warmer periods, a comparison between cooling with and without evaporative pads was performed, showing similar energy consumption. Full article

Today’s research on concentrated photovoltaic (CPV) cells focuses on creating multi-junction semiconductor solar cells capable of withstanding high temperatures without losing their properties. This paper investigated silicon low concentrated photovoltaic (LCPV) devices using Fresnel lenses. The parameters of the silicon CPV cell were measured to simulate its operation based on a single-diode model with four and five parameters. The most optimal position of the Fresnel lens relative to the solar cell was shown, and the dependence of the CPV efficiency on the concentration ratio, incident solar power, and temperature was studied. Experiments on heating of a solar cell were conducted to build a model of heating of a solar cell under different solar radiation based on machine learning. Additionally, a cooling system was developed, and experiments were conducted for one LCPV cell. The resulting LCPV model was used to predict electrical power output and temperature change pattern using clear day data. Results of modeling show increase in generated energy by 27% compared with non-concentrated solar cells. Cooling system energy consumption was simulated, and the optimum cooling regime was determined. The proposed LCPV system can be used as a hybrid heat and electricity source, increase power generation, and does not require new solar cell production technologies. Full article

With the prevalent use of large glazings, particularly in office buildings, offices receive an abundance of light and are among the largest consumers of electricity. Moreover, in an extreme hot arid climate such as in the UAE, achieving comfortable daylighting levels without increasing solar heat gain is a challenge, in which the window or fenestration design plays an essential role. This research adopts a case study of a higher education (HE) office building on the United Arab Emirates University (UAEU) campus, selected to investigate an evidence-based retrofitting solution for the west façade that can be applied in existing office buildings in the UAE in order to reduce cooling energy load as well as enhance indoor environmental quality. To achieve an evidence-based retrofitting solution, the research design built upon a comprehensive exploratory investigation that included indoor environmental quality physical monitoring and occupant satisfaction surveying. Model simulation was performed by means of DesignBuilder software to perform a single- and multiparameter sensitivity analysis for three key passive window design parameters, i.e., window-to-wall ratio, glazing type, and external shading, aimed towards minimizing annual cooling load and solar heat gain, while maintaining appropriate indoor daylight illuminance levels. The results highlight the importance of the window-to-wall ratio (WWR), as it is the single most significant parameter effecting total energy consumption and daylighting levels. The results recommend 20–30% WWR as the optimum range in the west façade. However, by utilizing high performance glazing types and external shading, equal energy savings can be achieved with a larger WWR. Double Low E tinted glazing and 0.4 projection shading overhang and side fin revealed a noteworthy reduction of energy use intensity of 14%. The study concludes with final retrofitting solutions and design recommendations that aim to contribute validated knowledge towards enhancing window performance in a hot arid climate to guide architects and stakeholders to apply a range of passive parameters towards reducing energy consumption and improving occupant comfort in office buildings. Full article

The operation strategies of a distributed energy system (DES) are usually proposed according to the electrical load (FEL) and the thermal load (FTL), which take the cooling/heating load or electric load as unique constraint conditions that result in a too high or too low equipment load rate. This paper proposes a new hybrid operation strategy (HOS) that takes the full utilization of natural gas and the minimization of power consumption from the power grid as constraints and coordinates the cooling/electricity ratio and heating/electricity ratio of buildings and equipment. In the optimization phase of a DES, an optimization method based on the discretization of the load is proposed to investigate the influence of the uncertainty of the load on the DES, which helps to avoid repeated load simulations and provides stronger adjustability by quoting the normal distribution function to obtain multiple sets of load data with different fluctuations. Further, a multi-objective optimization model combining the genetic algorithm (GA) and mixed integer linear programming algorithm (MILP) was established to find the optimal configuration of equipment capacities by comprehensively considering the annual total cost, carbon emissions, and energy efficiency of the DES. Finally, an office building example was used to validate the feasibility of the above theories and methods. Compared with the FEL and FTL, the HOS reduced the energy waste of the DES by 19.7% and 15.5%, respectively. Compared with using a typical daily load, using an annual hourly load to optimize the DES-HOS produced a better comprehensive performance and lower adverse impacts derived from load fluctuations. Full article