A Critical Analysis on investigation methods Used in Artificially Roughened Solar Air Heaters system :( A Review)

Abstract-Artificial roughness is useful on the absorber plate is the most common technique to get better thermal performance of solar air heaters. Experimental investigations related to distinct roughness geometries reveled that that the improvement in heat transfer is accompanied by significant rise in pumping power. Actually, a designer of roughness surface needs to carefully examine shape and compass reading of roughness elements in order to select the best fit roughness geometry for intended purpose. Furthermore it is essential to know how flow field is affected by particular roughness geometry so that direction of future researches could be conceived. So as to elucidate the useful findings an attempt has been made to review roughness geometries employed in solar air heaters. Some distinguished roughness geometries have been compared on the basis of heat transfer enhancements and thermo hydraulic performance to draw attention towards their usefulness for specific applications. Furthermore, light is frightened on different investigation method adopted for estimate of heat transfer and friction character of artificially roughened solar air heaters to identify features and limitations of each method. The method of Heat transfer by using artificially roughness are commonly used in various industries like process industries, heating and cooling in evaporators technique, thermal power station, airconditioning apparatus, refrigerators, radiators, automobiles etc.It has been observed that roughened absorber plate results augmented heat transfer coefficient at the cost of frictional penalty. This paper addresses different artificial roughness geometry using in heat transfer

Performance Improvement of Gas Turbine Power Plant by Intake Air Passive Cooling Using Phase Change Material Based Heat Exchanger

The power output of a gas turbine plant decreases with the increase in ambient temperature. Moreover, the ambient temperature fluctuates about 15–20°C in a day. Hence, cooling of intake air makes a noticeable improvement to the gas turbine performance. In this regard, various active cooling techniques such as vapor compression refrigeration, vapor absorption refrigeration, vapor adsorption refrigeration and evaporative cooling are applied for the cooling of intake air. This paper presents a new passive cooling technique where the intake air temperature is reduced by incorporating phase change material (PCM) based heat exchanger parallel to conventional air intake line. During the daytime, the air is passed through the PCM which has melting temperature lower than the peak ambient temperature. This will reduce the ambient air temperature before taking to the compressor. Once the PCM melts completely, the required ambient air would be drawn from the ambient through conventional air intake arrangement. During the night, when there is lower ambient temperature, PCM converts from liquid to solid. The selected PCM has a melting temperature less than the peak ambient temperature and higher than the minimum ambient temperature. It is observed from the numerical modeling of the PCM that about four hours are required for the melting of PCM and within this time, the intake air can also be cooled by 5°C. The thermodynamic analysis of the results showed about 5.2% and 5.2% improvement in net power output and thermal efficiency, respectively for four hours at an ambient temperature of 45°C.</jats:p

Performance Enhancement of a Refrigerator Using Phase Change Material-Based Condenser: An Experimental Investigation

Tropical countries like India, the ambient temperature reaches to 45–50[Formula: see text]C in the summer and higher ambient temperature directly impacts the energy required by the household refrigerator. This paper presents an experimental performance of a domestic refrigerator incorporated with a phase change material (PCM)-based condenser in parallel to the conventional wire-and-tube air-cooled condenser for the climatic conditions of India. It is proposed to operate the refrigerator with the PCM-based condenser, while the ambient temperature is higher during the day, otherwise with the air-cooled condenser. Due to large latent heat storage capacity of the PCM, the condenser temperature would not increase significantly. The COP of the PCM-based condenser was 28% higher as compared to air cooled condenser for 60[Formula: see text]min which reduce to 3% as PCM temperature reached to 33[Formula: see text]C. The energy consumption is lower by [Formula: see text]% in [Formula: see text][Formula: see text]h of refrigerator experimentation with the proposed modification. </jats:p

Energy Efficiency Improvement of a Refrigerator Integrated With Phase Change Material-Based Condenser

Abstract Energy consumption of a household refrigerator majorly depends on the ambient temperature and is highest at the noontime and lowest at the night. To mitigate the impact of higher ambient temperature, condenser of the refrigerator is modified by incorporating phase change material (PCM) in it. This article presents the development of numerical model of the PCM-based condenser and its comparison with the experimental model. A 3D numerical model for a PCM, namely, FS21-based condenser has been developed in commercial software ansys fluent 16.2, and the simulation outcomes are compared with the experimental test results. A correlation of a coefficient of performance (COP) which is a function of PCM temperature has been proposed. Based on the developed numerical model and the correlation, two other PCM-based heat exchangers, RT25 and RT25HC, are also analyzed numerically and their PCM temperatures are predicted. At the end, COP of the refrigerator with each PCM is compared.</jats:p

Theoretical Study of Energy Saving Through Redesign of Water Distribution Arrangement in a Medium-Rise Residential Building

Abstract The development of medium-rise buildings for the residence is the basic necessity to accommodate the growing population of countries like India where the residential land per capita is very small. Moreover, because of the energy shortage, energy-efficient development is the primary objective in the present scenario. With the efforts of reducing energy consumption in the medium-rise buildings, redesign of the water distribution system has been proposed in this study. In this proposed arrangement, two water pumps are placed at two different elevations, namely, ground and middle levels of the building. The first one at the ground level supplies water first to the middle floor flats and the second one at the intermediate level does for the middle to the top floor flats. Various building heights and pumps are studied theoretically and the analysis of the results shows that about 20% of the total pump energy can be saved by changing the way of water distribution in the residential buildings. Yet further energy-saving potential is available through the selection of better efficiency pumps. Moreover, reduction in pressure of the water at the lower floor flats is an additional advantage of the proposed arrangement.</jats:p

The study of Elastic Modulus and Thermal Conductivity of Different Fiber Cross-section of Fiber-Reinforced Composite in ANSYS

Abstract This work aims to predict the elastic modulus and effective thermal conductivity of the fiber-reinforced polymer composites. A representative volume element (RVE) of size 420 × 420 × 420 micron has been created in Solid-works with 10%, 17%, 27%, 40%, and 54% of fiber volume. The fiber of circular, square, and hexagonal cross-sections are considered in this analysis. The symmetric boundary conditions are applied to the RVE for determining the elastic modulus of the fiber-reinforced polymer. It has been observed from the ANSYS that the results are not exactly similar to the rule of mixture. The results are varying with a change in the cross-section of the fiber. It has been observed that elastic modulus is increasing with the increase in fiber density. It is also noticed that the elastic modulus is increased when the cross-section changes from circular to square to a hexagon with all said fiber volume. It is attributed that due to an increase in the fiber-matrix contact surface area, the adhesion between fiber and matrix increased. Surprisingly it observed that in all the cases the elastic modulus has decreased after 40% of volume fraction. This may be endorsed that due to higher fiber volume fraction the adhesion between fiber-matrices is not appropriate. Further study has revealed that the modulus of the composite is in accordance with the rule of the mixture when RVE has been prepared with a combination of circle, square, and hexagon. The effective thermal conductivity of the same RVE model has been carried out in ANSYS. It has found out that effective thermal conductivity is in reasonable agreement with the rule of mixture.</jats:p

Structural Analysis of A Two-Wheeler Disc Brake

Abstract Automotive brakes have come a long way, from drum brakes being widely used for a long time until disc brakes came along and began slowly wiping out the usage of drum brakes. This is primarily due to the number of advantages that the disc-pad setup brings - better stopping distance being one of the most important aspects of any braking system. Apart from this, key advantages of disc brakes over drum brakes include better heat dissipation, fade resistance, self-adjusting ability, compact packaging and so on. Although drum brakes too have certain advantages over disc brakes with lesser cost of manufacturing being one of them, the pure superiority of disc brakes outweighs the few benefits of the drum brakes and this has also reflected in the market. However, there is always scope for improvement when it comes to the structural and thermal characteristics of the brake disc. Researches have been carried out to discover better suited materials and brake disc designs to improve the overall structural and thermal characteristics and reduce uneven wear, squealing etc. The aim of this research is to analyze a new design and material combination based on earlier researches to decrease the deformation and provide a base for improving thermal characteristics.</jats:p

Gas Turbine Inlet Air Cooling Using Vapor-Adsorption Refrigeration Driven by Power Plant Exhaust

Turbine inlet air cooling (TIAC) has long been the most commonly used method to improve the performance of gas turbine based power plants. It is particularly effective in regions with high ambient temperatures. With growing energy demands and higher ambient temperatures around the globe, it is important to look beyond cooling cycles like vapor-absorption and vapor-compression which have certain limitations. It is prudent to use a vapor-adsorption cycle for TIAC since the waste exhaust heat can be utilized as the power source for adsorption compressor, resulting increase in thermal efficiency of the power plant. Also, the scalability of adsorption cooling from mere Watts to hundreds of kW and its ability to function using lower temperature heat sources (as low as 60 °C) render it highly suitable for TIAC. In this paper, a gas turbine power plant and a TIAC system running on vapor-adsorption cycle are mathematically modelled and thermal analysis involving comparison of performance of the power plant with and without inlet air cooling at various ambient and desorption temperatures is presented. Performance parameters analyzed include net power output and thermal efficiency of the power plant and the COP of the chiller. The results show that vapor-adsorption system has huge potential to be integrated with gas turbine power plant for inlet air cooling.</jats:p