• Energy Research

This article presents a comprehensive study on thermal and computational fluid dynamics (CFD) analysis of an innovative greenhouse dryer designed for passive operation under a no-load condition. The dryer incorporates hybrid thermal storage at the floor and a reflective mirror with thermocoal as the north wall, transforming a classical even-span greenhouse dryer into an efficient and effective system. The experimentation was conducted under clear sky conditions, with variations in global solar radiation (GSR) ranging from 166.6 to 1209 W/m2, resulting in an average value of 875.9 W/m2. The variations in GSR influenced other ambient parameters, including ambient temperature (28.7 °C to 35.6 °C), ambient relative humidity (33.2% to 45.7%), and ambient wind speed (0.1 to 1.02 m/s). Indoor parameters of the proposed dryer, such as inside temperature (31 °C to 47.35 °C), inside relative humidity (31.1% to 39.1%), ground temperature (44.2 °C to 70.6 °C), and outlet temperature (29 °C to 45.35 °C), were measured hourly. The average values of these parameters were 41.25 °C, 35.31%, 61.65 °C, and 39.25 °C, respectively. Quantitative parameters, including heat loss, overall heat transfer coefficient, coefficient of diffusion, and instantaneous efficiency, were calculated to evaluate the dryer’s performance. The proposed dryer exhibited an improved range of overall heat transfer coefficients (3.87 to 5.03 W/m2 K) compared to the modified greenhouse dryer under passive mode and the conventional greenhouse under passive mode. CFD analysis provided temperature distribution plots showing a progressively increasing range of temperatures near the trays, ranging from 310 K to 335 K, suitable for natural convection drying. The findings highlight the superior performance of the innovative dryer compared to contemporary systems. This research contributes to the advancement of drying technology and holds potential for applications in the agriculture and food processing industries.

This work focuses on daylighting performance analysis and its energy savings potential for residential building by using dynamic simulation and its experimental validation. The thermal performance of nano building material and its comparison with conventional building material has also been analyzed. The daylight factor was found in between 1 and 11% and 1–21% for the floor and wall, which is within the thermal comfort limit. The theoretical model results are compared with experimental values. The best building orientation was found to be 180° from the north or towards the south. Wind speed was found to be more than 30 kmph, which is used effectively in the natural ventilation of the building envelop. It leads to optimization of the room temperature. The heat transfer parameters, including the quantity of heat lost and gained through fabrics, thermal properties of nanomaterial have been compared with conventional building materials. The U value (heat loss coefficient) of building material defines building performance at a particular orientation. The U- values decreased to 8 times in-wall and 8.67 times in the roof of the building envelope compared to conventional building material. The model was experimentally validated, and there is close agreement between simulated and experimental daylight factor values with root mean percentage error of 1.24%. The total uncertainty in experimental measurement was found out to be 0.1421%, which is within the expectable range. Present study can be implemented in any building design with minimum modifications in any part of the world.

Latent heat thermal energy storage system can help in the smooth operation of energy supply and demand. In the present work, experimental study was performed to analyze the heat transfer rate of phase change material inside an annulus. A copper pipe (centrally loaded) runs the length of a cylindrical container during both discharging and charging modes. The overall heat transfer rate is enhanced during phase change process by adding longitudinal fins with the copper pipe. These longitudinal fins were tilted at an angle of 120⁰. Paraffin wax is used as phase change material. The main objective of the experiment is to analyze the heat transfer rate during the solidification and liquefaction of PCM. Also, the effect of mass flow rate and inlet temperature of heat transfer fluid was analyzed. Conduction was found to be the primary heat transfer mechanism during the initial stages of charging. Once the PCM get liquefied inside the system, natural convection gets dominated. During the solidification of PCM conduction heat transfer get dominated. Also, it was observed that melting duration is strongly affected by the inlet temperature of HTF while the flow rate slightly affects the melting duration.

AbstractFood losses and hunger around the world are majorly attributed to the lack of diverse food processing technologies and standardized methods. Solar energy is a potential solution for drying agricultural products, but traditional solar drying methods are not yet widely used. This study developed a finite element model using COMSOL Multiphysics to assess the performance of a passive greenhouse dryer for drying food products. The proposed model was used to simulate the drying of potato slices, and the results showed that the dryer was able to reduce the moisture content of the potato slices from 1 to 0.005 in 3 h. The drying efficiency was 20.52%, the relative humidity inside the drying chamber was 25.2%, and the energy and exergy efficiencies were 63.46% and 94.01%, respectively. Overall, the results of this study suggest that the passive greenhouse dryer is a suitable drying method for potato chips. The model developed in this study can be used to further optimize the design of the dryer and to evaluate its performance for other food products.

Fossil fuels are a finite resource that is becoming increasingly expensive. Solar energy is a renewable resource that has the potential to provide a lifetime supply of energy. Parabolic trough solar collectors are a type of solar thermal collector that can be used to generate electricity. This paper discusses the potential advantages and challenges of using parabolic trough solar collectors. One of the main advantages of parabolic trough solar collectors is their scalability. They can be used to generate electricity on a small scale, such as for a home or business, or on a large scale, such as for a power plant. Parabolic trough solar collectors are also reliable and have a long lifespan. They are not as susceptible to weather damage as other types of solar collectors, such as photovoltaic panels. However, there are some challenges associated with using parabolic trough solar collectors. One challenge is that they require large land areas. Another challenge is that they can be expensive to maintain. Despite the potential, further research is essential to address these issues. Future prospects lie in optimizing land use, enhancing maintenance strategies, and advancing collector technology to harness the full potential of parabolic trough solar collectors. Overall, parabolic trough solar collectors are a promising technology for generating electricity from solar energy. However, more research is needed to address the challenges associated with this technology.

The simultaneous impact of a building's electricity consumption and thermal performance is analyzed in this paper by taking a thermal model of a retail building located in Ranchi, India. A Baseline design of retail building having a rectangular footprint area is compared with four buildings with different footprint areas (Rectangular, T, L, H and U), in the South-West orientation. The thermal models for lighting of retail building are developed using eQuest software, and results obtained were validated experimentally. Intensity of light is reduced by 35% in baseline building corresponding to the amount of energy saved by upgrading to a T8 fluorescent fixture from a T12 fluorescent fixture. Average daylight factor of retail building in hot summer was found to be 34.80% experimentally and 28.98% through simulation. Based on energy consumption it is found that, for temperate buildings with rectangular footprints, buildings with L footprints, and buildings with H footprints are preferable when targeting net-zero energy status. The results encourage architects and engineers to work out an effective framework to enhance the use of natural illumination energy and suitable lighting according to buildings layout.

AbstractAn experimental investigation has been carried out on the modified greenhouse dryer with insulated north wall operating under natural convection mode of heat transfer for different floor conditions, namely ground floor, concrete floor, gravel floor, and black painted gravel floor. The terms like coefficient of diffusivity, coefficient of performance, overall heat transfer coefficient, heat loss factor, and heat utilization factor has been calculated for different floor conditions. The maximum difference between room temperature and ambient temperature was found to be 32.4°C at 13 O'clock for black painted gravel floor, followed by gravel floor, concrete floor, and ground floor which are 27, 14.1, and 11.5°C, respectively. It has been observed that the rise in the percentage of maximum room temperature in comparison to maximum ambient temperature for black painted gravel floor, gravel floor, concrete floor, and the ground floor was 50.31, 46.15, 30.1, and 26.6%, respectively at 13 O'clock. It has been found that the maximum temperature absorbed by black painted gravel bed. Hence, this type of floor condition is highly recommended for drying of low and medium moisture content type vegetables and fruits. The thermal parameters of the result obtain from the present setup was compared with the published literature, and it was found that all parameters show the similar trends; however, the present setup shows the superior performance compared to other research work.

The use of solar stills in rural regions are becoming increasingly popular as it is an economical solution for drinking water from saline water sources. Many researchers have worked for the improvement of conventional solar still to enhance productivity. Costly and time-consuming processes of operation in solar stills encourage many scholars to analyze mathematical simulation. This paper presents comprehensive reviews of the application of different design software to solar still systems. Design software is essential for developing and analyzing the mathematical models and predicting the most suitable performance parameters for the enhanced production rate of distilled water for still systems. Numerical modeling of solar still systems is necessary to analyze and investigate air movement, temperature variation for knowing water temperature, and air temperature through software like CFD, MATLAB, FORTRAN, TRYNSYS AutoCAD. The simulation technique's application using CFD is made with TRNSYS, FLUENT, ANSYS, FORTRAN and MATLAB which are useful tools to develop such mathematical models for the prediction of flow parameters. Engineering Equation Solver (EES) package and COMSOL Multiphysics solve the differential energy balance equation. All newly developed software employed for the utility of still solar systems is discussed. This article provides a comprehensive overview of the various software tools used in solar still to help researchers, scientists, and academicians.