International Journal of Energy and Environmental Engineering

Over the most recent couple of decades, tremendous consideration is drawn towards photovoltaic–thermal systems because of their advantages over the solar thermal and PV applications. This paper intends to show different electrical and thermal aspects of photovoltaic–thermal systems and the researches in absorber design modification, development, and applications. From the previous review articles, it has been concluded that the heat energy exhausted from the PV module can be further utilized in different ways and helps in achieving better efficiency. Furthermore, the types of photovoltaic–thermal systems such as air collector, water collector, and combi system, coupling with heat pump and their application to buildings are also stated. This paper also discussed certain design aspects like modifications in the flow channel by adding fins, thin metallic sheets, roll-bond absorber, and porous media and the effect of these modifications on the hybrid system’s efficiency. Furthermore, the use of the latest technologies such as nanofluids, thermoelectric generators, and phase-change materials improves the overall system performance. The role of soft-computing techniques is forecasting the impact of various parameters on the photovoltaic–thermal system is also discussed.

Waste heat recovery along with low-grade energy can be utilized for numerous applications in our daily life. This manuscript presents a novel idea of utilizing the waste heat from domestic cooking devices for assisting the solar desalination system through simulation and validated experimentally. To assess the potential of waste heat from a 2D axisymmetric model of water jacket has made using ANSYS Fluent while applying the user-defined function (UDF) to the outermost wall of the cookstove having the temperature as high as 340 °C during the operation. Further, to ensure the recovery of the waste heat, without affecting the performance of the cookstove, an air gap of 0.05 cm was provided between the combustion chamber and the water jacket. The efficiency of the original cookstove without air gap was found to be ~ 33%, which enhanced up to ~ 43.79% without flow of water in the jacket, and finally reached up to 56% when water flows in the jacket. This indicates that the arrangement used in this particular study has not only recovered the waste heat but also improved the overall performance by ~ 69.34%, without disturbing the cooking phenomenon.

This research investigates the effectiveness of loops and paths as embedded in a modified pinch package (Aspen Energy Analyzer), that comprises a blend of traditional pinch technique with mathematical programming, in simultaneous optimization of total annual cost (TAC) in heat exchanger network synthesis (HENS). It uses composite curves, grand composites curves, supertargeting and looping system just as in pinch, as well as linear programming and mixed integer linear programming (MILP) in the design of HENs. The tool was adopted in solving some literature problems that had earlier been solved using pinch and mathematical programming techniques. The results obtained compared well with those of various authors that used different techniques as shown in the tables of cost comparison in this paper. The loop and path optimization technique adopted in this research obtained the least TAC in four out of five problems solved in this paper. This shows that loop and path optimization as available in a software-combining pinch and mathematical programming can be more effective than various other methods that have been adopted in the literature. It further demonstrated that no particular technique can return the lowest TAC for all HENS problems.

The present study presents an enhancement in wick solar stills performance depending on using different aspect ratios with the same project area and wick materials, glass cover cooling, and external reflectors after practical knowledge of the best wick material type and dimensions. The proposed three stills (A), (B), and (C) have evaporation area dimensions of 1 × 0.85, 1.5 × 0.57, and 2 × 0.425 m2, with an aspect ratio of 1.18, 2.63, and 4.71, respectively. The results revealed that the solar still with medium dimensions set has the best performance. Also, adding a top and bottom reflector to type (B) solar still with cotton cloth wicks increased the freshwater productivity and energy efficiency by 37.99 and 39.96%, respectively, compared to type (A) solar still with cotton cloth wicks. Moreover, the cost of one liter of freshwater distillate was decreased by 1.82%. Applying glass cover cooling on type (B) solar still with cotton cloth wicks increased the freshwater productivity and energy efficiency by 30.59 and 33.13%, respectively, compared to type (A) solar still with cotton cloth wicks. Furthermore, we have a decrement in the cost of one liter of freshwater distillate by 7.69%. Moreover, adding reflectors and cover cooling together to wick solar still increased the freshwater productivity and energy efficiency by 52.36 and 58.5%, respectively. On the other hand, the cost per liter of freshwater was reduced by 9.8%.

Variable refrigerant flow (VRF) air conditioning systems have become highly preferred in the air conditioning sector has enabled many new companies to enter the industries of VRF Air Conditioning Systems manufacturer and applicant. It has become difficult for decision-makers to select the best applicant company among the alternatives. In this article, the applicant company selection model is developed for heat-pump VRF air condition systems to meet the heating and cooling needs of buildings. The operation and structure of the VRF systems and their selection criteria are determined for the applicant company. Using the Preference Ranking Organization METHod for Enrichment of Evaluations (PROMETHEE) method, one of the multi-criteria decision-making methods, an application company selection model has been presented for three different buildings according to the building characteristics and climate conditions.

Corn stover (CS) and biosolids (BS), two easily accessible biomass (BM) resources, were combined in Co-pyrolysis (Co-Pyr) and Co-hydrothermal carbonization (Co-HTC) processes. The beneficial or catalytic effects of BS on CS in this process were identified by characterizing the following measured parameters of the produced char: ultimate and proximate analysis, higher heating value (HHV), van-Krevelen-diagram, activation energy (AE), and combustibility index S. The influence of the BS on CS was indicated by comparing the stated values of the CS/BS-mixed samples with the results of the pure BS- and CS-samples and the values of the unprocessed original BS and CS. The following developments were recognized: HHV of pure CS increased to 21–23 MJ/kg, that of pure BS was reduced to 7–9 MJ/kg, and for the mixed samples, one CS:BS-ratio showed beneficial interactions and resulted in 20–21 MJ/kg. The carbonization rate was advanced for the Pyr samples, ranging in the areas of coal and lignite, and most HTC samples in the area of peat and the original BM. The AE decreased from 65 and 41 kJ/g for the starting materials to an average of 30–40 kJ/g for most samples, and several samples reached 20–25 kJ/g. Hydrochars made from combined BM presented advanced combustibility index S values, passed 1 × 10–6, compared to Co-Pyr, and its biochar did not reach this combustibility index. CS and BS in pure and mixed forms, treated with Pyr or HTC, led to advanced solid fuels for different aspects of the analysis focus and depending on the composition of the sample.

Việc định tuyến các đường dây truyền tải điện cao thế để kết nối các nhà máy năng lượng tái tạo phân tán là một vấn đề quan trọng từ góc độ môi trường. Một phương pháp chuẩn mà xem xét từ nhiều khía cạnh, các yếu tố ảnh hưởng và có khả năng điều phối giữa các ràng buộc có trọng số có thể là một công cụ hữu ích cho các cơ quan quản lý tham gia vào quy trình phê duyệt. Phương pháp này có thể là một hỗ trợ hiệu quả để tăng độ tin cậy, tiết kiệm chi phí cho người tiêu dùng và giảm thiểu các tác động không thể tránh khỏi của các đường dây đối với cộng đồng dân cư xung quanh. Trong bài báo này, chúng tôi điều tra tính thích hợp của một quy trình được sử dụng bởi Terna, nhà điều hành hệ thống truyền tải điện cao thế của Ý, để xác định các hành lang mà đường dây truyền tải điện mới sẽ được thiết lập với tác động môi trường thấp nhất. Phương pháp này dựa trên việc phân chia tất cả các ràng buộc liên quan do các vấn đề môi trường và quy định lãnh thổ thành bốn lớp chính. Một nghiên cứu trường hợp thực tế liên quan đến thiết kế và kết nối một trại gió đặt gần Collarmele, ở trung tâm nước Ý, cho thấy hiệu quả của phương pháp được đề xuất.

This paper examines the effect of building shape, zones, orientation and window to wall ratio (WWR) on the lighting energy requirement and the thermal comfort in the naturally ventilated houses in tropical climate. The lighting electricity and the adaptive thermal discomfort hours (ASHRAE 55 80% acceptability) of 300 different models of two-storey houses were obtained using Design Builder simulation software. The models were developed for three building shapes (square, rectangle and L-shaped) and the orientation of each model was changed for 24 orientations and four window to wall ratios. Results indicate that the rectangular shape with staircase positioned in the middle of the house will provide higher thermal comfort for WWR of 20 and for other WWRs the L-shaped models provide higher thermal comfort when the staircase is positioned at the short corner or middle. The square-shaped houses with staircase at the middle have the highest lighting electricity and the L shape has the lowest lighting electricity. Further, WWR changes the thermal comfort by 20–55% and the percentage change in lighting electricity due to WWR is only 1.5–9.5%. Therefore, thermal comfort should receive more attention in deciding the WWR. Moreover, the results show an effect when the zone sizes and location change.