Energy Performance Evaluation Research Articles

A comprehensive investigation of PCM based annular thermoelectric generator for energy recovery: Energy conversion characteristics and performance evaluation

Annular thermoelectric generators (ATEG) are increasingly attracting attention and are pivotal in thermal energy recovery due to their unique characteristics, which can be perfectly adapted to cylindrical heat sources. Considering the efficient thermal management and power generation of thermoelectric generator (TEG), phase change material (PCM) can be integrated with the cold side of TEG as a favourable cooling medium to meet its functional requirements. However, previous studies have focused on the intrinsic connection between flat-plat TEG and PCM, while the impact of PCM on ATEG has not been systematically explored. In the present study, an annular thermoelectric generator with PCM (ATEG-PCM) under a pulsed heat source is proposed, and its dynamic characteristics and energy distribution are evaluated. The effects of PCM parameters such as height, latent heat and melting temperature are comprehensively explored from multi-index, including PCM temperature, liquid fraction, temperature difference, output power, energy and exergy efficiencies. Furthermore, a comparative investigation of ATEG-PCM, PCM-ATEG where PCM is applied on the hot side, and ATEG without PCM is further carried out to clarify the coupled mechanism of PCM on thermal management and power generation enhancement of ATEG. The results indicate that the energy efficiency of ATEG-PCM has saturated at PCM height of 10 mm to 12 mm, while the exergy efficiency merely slightly increases. Especially, the PCM melting temperature merely affects the time at which PCM initiates to change from solid state to liquid state, without affecting the total energy efficiency of ATEG-PCM. Furthermore, the comparison analysis determines that ATEG-PCM deserves more attention, judging by thermal management and power generation. This work not only contributes to the understanding of the coupling mechanisms between PCM and ATEG but also provides a research direction for energy recovery in PCM based ATEG hybrid system.

Design optimization and energy performance evaluation of a dedicated outdoor air system with dual cooling sources

Dedicated outdoor air systems can save cooling energy and improve thermal comfort compared to conventional air-conditioning systems. Although many studies have investigated the energy performance of dedicated outdoor air systems for a certain application, there is a lack of a modeling resource to investigate with how the designs of the system are coordinated with control strategies aiming to improve its energy efficiency. This paper aims to optimize dedicated outdoor air system designs and develop a flexible model to evaluate the performance of the system. First, two innovative energy-saving designs of dedicated outdoor air system with dual cooling sources were proposed. Alternative design 1 optimizes the structure of the fresh air unit, while alternative design 2 builds on alternative design 1 by coupling it with a heat recovery system. Then, the two innovative systems and a baseline design were modeled using the equation-based Modelica tool. Finally, the energy performance of the three systems was evaluated under a hot and humid climate. Results showed that the Modelica-based models are able to capture the transient control strategy details. Alternative design 2 was found to be the optimal design among the three designs, with the highest energy efficiency ratio of chiller plants at 5.3. Moreover, it can reduce the cooling load supply by 9.3% and save about 7.4% on the energy consumption of chiller plants compared to the baseline design. In addition, alternative design 2 has a payback period of only 2.7 years, compared to the baseline design. It reveals the benefit of the heat recovery system in reducing the energy consumption and the cost of the cooling system. The developed dedicated outdoor air system simulation model can provide an evaluation for further improving the system optimization design, control strategy, and equipment configuration in engineering applications.

Predicting energy performances of buildings' envelope wall materials via the random forest algorithm

PurposeNumerous simulation software has been used to evaluate energy performance with 12% of the research focusing on long-term energy consumption prediction. This paper aims to utilize machine learning to predict the energy performance of building envelope wall materials over extended periods. MethodologyIn our work, machine learning model learns from a large set of building envelopes simulated using the Integrated Environmental Solutions Virtual Environment as follows: FindingsMachine Learning models can also be used to predict the impact of building design and construction characteristics on energy consumption, showing that factors such as wall thickness, orientation, and thermal mass indicated lower relative standard error (<0.001); however, not all of them were statistically significant (p > 0.05). While the overall model indicates statistical significance (p = 2e-16), the multivariate linear regression model produces R2 value of 0.42, indicating a weak relationship between predictor variables and target attributes. OriginalityThe utilisation of Random forest algorithm for the wall envelop energy consumption Research implecationdifferent to other techniques, our proposed approach addressed the issue related to building envelop for new constructions to assist professional from construction industry.

Appropriate level of development of in-situ building information modeling for existing building energy modeling implementation

Existing buildings deteriorate over time, and the energy consumption continues to increase. In order to improve energy efficiency, evaluation of the energy performance of the existing buildings through simulation is required in advance. However, for most existing buildings, drawing information for evaluating energy performance is omitted. Without drawing information, the building energy cannot be modeled and energy cannot be predicted. To solve this problem, the building information modeling (BIM)-building energy modeling (BEM) process based on 3D laser scanning has recently been attracting considerable attention. When there is no drawing information in this process, geometric information of the existing building can be implemented through BIM. In addition, it is extremely important to determine the level of development (LOD) of the BIM because the accuracy of energy prediction depends on the LOD. In other words, the LOD of in-situ BIM should be determined for accurate building energy performance evaluation. Therefore, this study proposes an appropriate LOD of in-situ BIM for BEM implementation of existing buildings. Accordingly, the BIM-BEM process was applied and the building energy performance was evaluated. In addition, the uncertainty and accuracy were analyzed through comparison with the measured building energy consumptions. As a result of the analysis, LOD 350 was determined as a suitable LOD, capable of simulating the energy performance of an actual building.

Battery Electric Tractor Powertrain Component Sizing With Respect To Energy Consumption, Driving Patterns and Performance Evaluation Using Traction Motor

In this paper sizing the powertrain of battery electric tractor (BET) including major farming implements are investigated for various real world driving patterns. Powertrain components are modelled using torque-load characteristics which are function of speed, acceleration, plowing implement and depth of plowing and texture of the soil. Effect of load variations on powertrain performance and energy consumption are also explained in detail. In this powertrain design major farming implements like chisel plough, mould board plough, field cultivator, sweep plough are considered. Tractor hauling a trailer carrying goods with 2000 kg weight is also considered for powertrain design. Typical operating velocities of 18, 15 and 25 kmph are taken for sand, tillage and asphalt surfaces respectively for tractor trailer applications and 7 kmph for plowing applications. The dynamic model of the powertrain is modelled in MATLAB/SIMULINK. PMSM is selected as a traction motor and its performance is evaluated in MATLAB/SIMULINK. Same has been verified using real-time Hardware in loop (HIL) simulator with help of OPAL-RT (OP5700).

Energy performance evaluation of bifacial solar photovoltaic modules in Hong Kong

Despite the proven benefits of solar bifacial photovoltaic (BPV) over monofacial PV (MPV) systems, the feasibility of the technology in subtropical climate regions has not been evaluated. Thus, this study provides a comprehensive energy performance evaluation of BPV in Hong Kong using numerical simulation and on-site experimental validation. Three types of solar PV modules, i.e. monofacial PV, framed BPV and frameless BPV, are studied experimentally under different tilt angles, mounting heights and slope orientations. The obtained field measurements and simulation results show that the average bifacial gain (BG) of a BPV system can reach 7.9% and 11.6% when facing south, and up to 167% when facing east. Furthermore, it was observed that an increase in tilt angle also influences the BG performance, and the annual electricity yield can be maximised by increasing the ground albedo through white painting on the roof surface. Finally, the obtained results in this study validate previous studies’ assertion that BPV is a viable option over MPV and provides a starting point for the adoption of BPV in subtropical climate regions, especially in Hong Kong.

Impacts of architectural beauty to building energy performance

Consideration of architectural beauty in the built environment is growing as the broader concept of sustainable design replaces the more narrowly defined concepts of high performance or green building. This work is a part of Beauty in Building (BiB) research conducted by a team of architects and engineers working to understand links between architectural beauty and building performance. This work presents the exploration findings on what impact architectural beauty may have on building energy performance. A sample of 35 case studies contrasting high performing buildings with architecturally beautiful and high performing buildings was evaluated using the developed BiB matrix. Features that distinguished the best performing buildings from the rest of the sample population were identified based on the results of the case study evaluation. Building energy models representing these building features were then developed for quantitative evaluation of energy performance through energy simulation. Relative importance to beauty and energy performance of each of the features was determined and presented as weighting factors. The results illustrate those features that exhibited density, a combination of multiple systems, in the designs offered better performance relative to both beauty and energy.

Energy performance evaluation of alternative energy vectors for subsonic long-range tube-wing aircraft

Energy performance evaluation of alternative energy vectors for subsonic long-range tube-wing aircraft

A Suggestion of the Alternatives Evaluation Method through IFC-Based Building Energy Performance Analysis

In a rapidly changing modern society, the construction industry is facing various issues, including the Fourth Industrial Revolution and climate change. Research on convergence between technologies such as artificial intelligence, AR/VR, IoT, and metaverse, and sustainable technologies such as green buildings and eco-friendly energy is being attempted in each field. The most important thing in the development of these technologies will be the interoperability of data. BIM is a technology that can effectively store data regardless of the size of a building or the amount of information and can be shared and stored without loss of data through an open format called IFC (industry foundation classes). This study aims to present a plan to generate alternatives and evaluate energy performance by analyzing the shape of the envelope for amorphous buildings through IFC. Design elements were derived through analysis of previous studies, and alternatives were automated by developing interfaces that can generate shapes according to the derived design elements. The generated alternatives can be compared and analyzed through the analysis of building energy by developing an evaluation system based on IFC. Based on the quantitative results in the initial design stage, the reliability of the design proposal considering the performance of the building is improved, and the process and cost can be predicted in advance; thus, it is expected to be an efficient decision support tool.

Energy and exergy performance evaluation of a novel low-temperature physical energy storage system consisting of compressed CO2 energy storage and Kalina cycle

To improve the overall performance of the Compressed CO2 Energy Storage (CCES) system under low-temperature thermal energy storage conditions, this paper proposed a novel low-temperature physical energy storage system consisting of CCES and Kalina cycle. The thermal energy storage temperature was controlled below 200 °C, and the Kalina cycle was used to optimize the reuse of the stored thermal energy. A thermodynamic model of the integrated system was constructed, and the system performance was analyzed from the energy and exergy perspectives. Several evaluation indicators, such as system exergy efficiency (SEE), round trip efficiency (RTE), system energy density (SED), Kalina exergy efficiency (KEE), and Kalina energy efficiency (KEnE), were defined to evaluate system performance. In addition, the influences of several core parameters (e.g., split ratio (r), storage pressure (ps), turbine efficiency (te), pinch point temperature difference (pt) of heat exchangers, and ambient temperature (T0)) on the system performance were analyzed. The results of the base condition showed that SEE, RTE, SED, KEE, and KEnE were 58.17 %, 59.38 %, 6.32 kWh/m3, 38.62 %, and 8.64 %, respectively. The exergy destruction in heat exchanger 3 was the largest, accounting for 71.7 % of total exergy destruction. The sensitivity analysis results showed that increasing r could increase the SEE of the system, increasing ps could lead to a decrease in the RTE of the system, and increasing T0 could cause the RTE and SED to increase. The increase in te could improve all evaluation indices, while the increase in pt could reduce the system's overall performance. This study provides a new solution for the integrated application and optimal design of CCES systems under low-temperature thermal energy storage conditions.

Energy Indicators for Enabling Energy Transition in Industry

Energy transition is a fundamental process in the move towards sustainable development, but in industry, it is complicated by the remarkable sectoral heterogeneity. Fostering the realization of energy transition in the industrial sector requires the characterization of its energy dimension, in terms of energy mixes and end-uses as the determinants of transition pathways, and energy solutions and tools as the enablers of this transition paradigm. We observe that the suitability of tools for energy analysis depend on trade-offs between comprehensiveness, ease of use, robustness, and generalization ability. In this regard, we discuss the appropriateness of energy indicators and provide an overview of indicator typologies, methodological issues, and applications for energy performance evaluation and improvement. With reference to the dairy processing industry, selected as a representative industrial branch, we outline current and desirable energy benchmarking applications and exemplify the effectiveness of energy indicators in the quantification of the potential of energy solutions. The obtained results are promising and suggest that researchers should further explore the novel applications of energy indicators for energy performance improvement. To foster the establishment of energy indicators in industrial practice and energy policies, we remark that cooperation between industrial stakeholders is essential.

Energetic and parametric studies of a basic hybrid collector (PV/T-Air) and a photovoltaic (PV) module for building applications: Performance analysis under El Jadida weather conditions

The photovoltaic thermal hybrid collectors represent one of the most used technologies in positive energy buildings, the device allows converting the available solar energy into heat and electricity at the same time. In this study, a comparative analysis is introduced between two different types of solar conversion devices: conventional hybrid solar air collector (PV/T-Air) and photovoltaic (PV) module. Also, a parametric study was performed to know the impact of different parameters related to the performance of both solar systems. A numerical system based on the fourth order Runge–Kutta iteration method, is used in this study, founded on a strong coupling between the heat balance equations and the different electrical and thermal parameters of both configurations that are included in this work. The energy performance evaluation was applied to the climatic conditions of El Jadida city, located in Morocco. The numerical results indicates that the estimated value of the daily average overall energy conversion efficiency attains: 30.22% for the PV module, and 52.14% for the examined hybrid air collector (PV/T-Air). These results are calculated with an air mass flow rate of 0.0215 kg/s, and these values are according to the meteorological data collected on the site of El Jadida city for a sunny day in July.

Thermal behavior and safeties of fine TAGzT and its CMDB propellants including characterization and energy performance evaluation

Thermal behavior and safeties of fine TAGzT and its CMDB propellants including characterization and energy performance evaluation

Energy and exergy performance evaluation of an ejector enhanced Joule-Thomson cycle with binary mixtures

Energy and exergy performance evaluation of an ejector enhanced Joule-Thomson cycle with binary mixtures

Evaluation of Energy Performances of Solar Dryers

In solar drying, the moisture content of a product is reduced through the use of sunlight. Solar drying is practiced since civilization for the drying of crops. The dried crop has a longer shelf life and requires less storage space. For crop drying, hot air is required in the moderate temperature range of 40 to 75℃. Solar dryer makes it possible to obtain better product quality. Over the past 20 years, numerous experimental projects have been carried out in the field of solar dryers. Most conventional dryers are not able to operate continuously during the off sunshine time. However, attempts were made to develop uninterrupted solar drying systems by incorporating an energy storage facility and a hybrid mode of operation. Sensible and latent heat storage methods are widely used to store solar energy. Heat storage materials store energy in the form of heat during sunshine and release it whenever it is required. Biogas backup, Chemical heat pump, Photo Voltaic, and Fluidized bed methods were integrated with solar dryers for uninterrupted operation. In this article, the discussion is made about different dryers. Also, the challenges and scope in the area of the solar dryer are highlighted.

Evaluating Energy Performance of Double Skin Facade Building

BIM means Building Information Modelling Management that people are able to design, create and maintain the building throughout the whole lifecycle. BIM technology provides a new design method that overall energy performance could be simulated and evaluated and it helps to achieve the sustainability goals. Transparent facade system on modern buildings usually causes high heating or cooling consumption. The double skin facade could be used as possible solution for these problems. A student work would be simulated in BIM and its double skin facade system would be evaluated to reduce energy consumption.

Energy performance evaluation of an axial-flow pump as turbine under conventional and reverse operating modes based on an energy loss intensity model

As a low-cost scheme for small-scale hydropower generation, pump as turbines (PATs) are used at different hydrosites around the world. Nevertheless, a big number of recently conducted studies on PAT performance have mainly focused on the centrifugal type, despite the fact that the axial-flow type has a comparatively large flow capacity, thus disposing of higher power density. Therefore, this article seeks to investigate the flow dynamics of an axial-flow PAT and associated energy loss characteristics, under both pump and turbine operating modes. It adopts the numerical simulation method and uses entropy production theory to propose an energy loss intensity model in the cylindrical coordinate system, which quantitatively gives the spatial variation pattern for energy losses in pump and turbine operating modes. In addition, the correlation between energy loss and flow instability is deeply analyzed, where the energy characteristics in pump and turbine modes are quantitatively evaluated. It is shown that the energy loss within the impeller and the guide vane flow fields, for both operating modes, is mainly because of the turbulent entropy production. The proportion of direct entropy production and wall entropy production is found to be relatively small. The velocity gradient, flow vorticity, turbulence intensity, and energy losses within the flow passages of the axial-flow PAT have been closely related. However, owing to the difference in PAT operating modes, there is a significant difference in the location of energy losses. The unstable flow phenomena, such as the impact at the blade inlet, flow deviation at the blade outlet, flow separation, back-flow, and vortex, are the main reasons for entropy production. This study serves as a reference for the design, optimization, and application of axial-flow PATs.

머신러닝을 활용한 건물의 기밀성능 예측 모델 개발

In this study, as a building energy performance evaluation value correction concept, a building airtightness prediction model was developed using a machine learning algorithm capable of regression analysis based on building airtightness data collected from literature and field measurements. R², MAE, MSE, and RMSE were used to evaluate the accuracy of the prediction model, and the RReliefF algorithm was used to evaluate the contribution of the building elements used in predicting building airtightness. The random forest model had the highest prediction accuracy. Among the building elements, the wall-to-window ratio had the most effect on the airtightness performance.

Evaluation of the Lighting Energy Performance of Educational Buildings with BEP-TR Methodology: The Case of ERU Faculty of Architecture

As part of energy efficiency and conservation measures, central and local governments have developed various action plans, international commitments, calculation models, regulations, standards, and certificates and arrangements. Building Energy Performance (BEP-TR), a national calculation method developed according to the conditions of Turkey, is one of them. With BEP-TR, the energy efficiency of the building is measured in existing or alternative situations. In public buildings, the issue of energy efficiency is vital in terms of being an example. In the framework of this study, the Faculty of Architecture of Erciyes University as an educational and public structure was selected as the study area. Lighting is essential in electricity consumption in public buildings, especially educational establishments. This study aims to guide the energy efficiency principles and lighting design on the axis of comfort-cost and consumption for all public buildings, especially educational buildings, by emphasizing that the concept of energy efficiency should be handled multi-dimensionally with its various layers. Current state data to measure using the BEP-TR will be assessed if the lighting is energy efficient, according to visual comfort needs. Lighting energy consumption values were recalculated by checking the alternatives, simulations, and visual comfort criteria developed concerning energy efficiency. With the revision of the lighting design, the amount of savings to be realized by the system that meets the requirements for visual comfort was calculated. While the improvements proposed in the study were handled under the title of the artificial lighting system, other parameters were kept constant. In improvements alternatives, while offering a physical and psychological enhancement for users, it also saves energy in public buildings and bring an ecological proposition to reduce the carbon footprint for nature. Considering the proposal in the context of comfort-consumption-cost and amortization. The calculation of how long the initial investment cost will be amortized with the amount of savings has been made using three different methods. The study shows originality in responding to the designer’s aesthetic concerns with the multi-dimensional inputs of energy efficiency.

Assessment of energy performance and GHG emissions for the urban water cycle toward sustainability

Abstract This study presents a holistic approach to evaluate energy performance and greenhouse gas (GHG) emissions from urban water supply and sanitation stages, which are important for sustainable water management and climate change mitigation. The study was conducted for Antalya city of Turkey to compare baseline and improved scenario conditions using the Energy Performance and Carbon Emissions Assessment and Monitoring (ECAM) tool. The current application of urban water and wastewater services was defined as the baseline scenario. For the improved urban water cycle, the reduction of non-revenue water, onsite sanitation prevention, increase in energy efficiency, biogas production and reuse of treated wastewater were investigated. Water supply and sanitation stages contributed to approximately 26 and 74% of total GHG emissions and 70 and 30% of energy consumption for the baseline scenario, respectively. GHG emissions were determined approximately as 52,423 tCO2eq/year for CO2 (40%), 47,029 tCO2eq/year for CH4 (35%) and 33,006 tCO2eq/year for N2O (25%) for the baseline scenario. The total GHG emissions of 132,457 tCO2eq/year and energy consumption of 136,328 MWh/year were reduced by 27.65% for GHG emissions and 16.48% for energy consumption for the improved urban water cycle. The outcomes of this research are expected to achieve sustainable cities and combat climate change.