V.K. Sharma

Design and performance studies of a solar dryer suitable for rural applications

Abstract This research paper is aimed at investigating means for food preservation using processes suitable for implementation in rural areas, where energy resources are scarce. Bearing in mind the low cost of capital investment and utilization possibilities, mainly agricultural drying, we have fabricated different types of solar dryers. Air flow in the drying system is by natural convection. The performance of the various types of solar dryers, along with a preliminary heat transfer analysis, is presented.

Theory of multiple-pass solar air heaters

We have developed the theory for a four-pass air heater. We have also studied the system performance with one, two, and three passes. The effect of the number of glass cover plates on one, two, and three passes has also been investigated. It is shown that the multiple-pass air heater performs well for low flow rates and large plate lengths. For small plate lengths and high flow rates, the addition of cover plates does not affect the performance of two- or three-pass air heaters.

Investigation of rock bed solar collector cum storage system

Abstract This paper presents an experimental investigation of a prototype rock bed solar collector. This collector consists of rocks in a galvanized iron box; the rocks are painted dull black and suitably glazed. The heat can be extracted by forced air convection. This system can act as a storage system, as well, when suitably constructed. The heat decay characteristic of the bed is also studied. A preliminary economic analysis of this air heater is presented.

Evaluation of the performance of a cabinet type solar dryer

Abstract In the present work, an attempt has been made to analyse a cabinet type solar dryer. The transient equations for the different components of the system are written, and their solutions are attempted within the framework of periodic analysis. This model is capable of predicting the instantaneous temperature inside the dryer, the moisture content and drying rates. The results obtained from the theoretical and experimental observations are reported in this research paper.

Experimental study of an inexpensive solar collector cum storage system for agricultural uses

Abstract This paper presents an experimental investigation of an Augmented Integral Rock System. Experiments have been performed on such a solar air heater fabricated at the Institute. Experimental observations of fluid temperature, energy storage and other measures of system performance with variation of air mass flow rate, number of glazings and depth of rock bed are presented. The heat decay characteristics of the rock bed, while using a night insulation cover in addition to glass covers, are also reported in detail.

Evaluation of a matrix solar air heater

Abstract This paper presents the theoretical analysis along with the experimental validation of a matrix solar air heater, with air flowing downward and upward through the matrix. The heat balance equations governing the behaviour of the system are solved explicitly. The results obtained from the analytical expressions for outlet temperature compared well with the experimental data. A preliminary economic analysis of the matrix air heater under investigation is also included.

Mathematical modelling and experimental evaluation of a natural convection type solar cabinet dryer

Abstract The general objective of the investigation described in this research communication is to discuss the design methodology, performance studies and analytical solution of a cabinet type solar dryer. Experimental results of different experiments conducted with different products, in a New Delhi climate, are included in this paper. The analytical solution is based on the principle of simultaneous heat and mass-transfer.

Transient analysis of a solar air heater of the second kind

Abstract This paper presents a theoretical analysis along with the experimental validation study of a solar air heater of the second kind. The heater consists of a flat passage between two metallic plates through which the heat transfer fluid air is made to pass by some auxiliary means. Study of the periodic response of different parameters of this solar air heater is attempted. The heat balance equations governing the behaviour of the system are solved explicitly. The results obtained from the analytical expressions for the transient variation of outlet air temperature compare well with experimental data. Predictions are also made regarding effects of different performance parameters of the air heater with variations of air mass flow rate and plate emissivity with the hope of optimizing the collector configuration.

Investigation on double-glazed solar air heater connected in series with rock bed solar collector-cum-storage system

Abstract This paper presents an experimental investigation along with a theoretical model of a double-glazed flat plate solar air heater connected in series with an integrated rock bed collector-cumstorage unit. Predictions are made regarding the effects of heat transfer coefficient and number of glazings on the performance of the air heater. The model fits quite well with the experimental observations.

Functional aspects of a porous bed solar air heater

We have developed the theory of a matrix air heater with a rear plate, investigated the role of individual components, and studied the performance differences for air flowing downwards and air flowing upwards through the matrix. The system is compared with an air heater of conventional design with flow between 2 plates.