Showing papers by "Shireesh B. Kedare published in 2020"

Appropriate household point-of-use water purifier selection template considering a rural case study in western India

Abstract: There is a wide range of household water treatment options available for a variety of contexts. Each water purifier has its own optimal range of operation. Simultaneously, the diverse environments and circumstances set different boundary conditions for such purifiers to operate successfully. In low-income countries, especially with unregulated and decentralised water supply mechanisms such as open wells, the use of point-of-use water purifiers is quite widespread. However, it is observed that the water purifier may not be appropriate to the prevailing context. Hence, this short review aims to introduce a wide range of water purification alternatives available for a family (of about 3–5 members) and the way they could be classified and reviewed. The perspective selected is that of a low-income rural household in coastal region of western India and the scenario of water quality which is primarily affected by physical and biological impurities and not necessarily severe chemical contamination. Based on this context, attributes are defined and prioritised; further, a scale to rate the purifiers is worked out. A selected number of point-of-use water purifiers for which data from the literature or field observations are available are reviewed against these attributes for the sample context chosen. This independent review methodology consists of setting the attributes and comparing the water purifiers based on the sum of prioritised scores and thus acts like a selection template and can be adopted to select the appropriate purifier for any other scenario accordingly.

The Validity of Approximate Boundary Conditions for Natural Convection With Thermal Radiation in Open Cavities

Abstract: The use of approximate boundary conditions at the opening of the cavities leads to restriction of the computational domain and, hence, the reduction in computational effort. However, the accuracy of the restricted domain approach (RDA) had been evaluated only for the natural convection inside open cavities and that too only for one aspect ratio (AR). The validity of the approach had not been evaluated for inclined, as well as, shallow cavities. This study focuses on the analysis of the accuracy of RDA against extended domain approach (EDA) in open cavities of different ARs, at different inclinations and different Rayleigh numbers (Ra). The results show that the difference between the approaches is only significant in very shallow cavities (AR is defined as the height of the hot wall divided by the depth of the cavity) at low Ra. For Ra higher than 106 and an AR greater than 0.2, the maximum difference between the two approaches is around 5% and hence RDA can be recommended in these ranges, resulting in increased computational efficiency without significant loss in the accuracy. Moreover, the maximum difference in the results for the two methods is for intermediate inclinations. Even there, an increase in the difference is more pronounced at lower Ra. Furthermore, distribution of the exit velocity and temperature at the opening as well as the distribution of the Nusselt number at the hot wall is compared for RDA and EDA to explain the behavior of error at different ARs and inclinations.

Multiscale Concentrated Solar Power

Abstract: This chapter highlights the multiscale concentrated solar power thrust, which focused on developing new low-cost manufacturable technologies for both high- and moderate-temperature thermal cycles. In the high-temperature range, the focus was on the supercritical carbon dioxide (s-CO2) Brayton cycle. Research involved developing low-cost heliostats coupled with novel bladed receivers and a novel CO2 test loop. A key focus was developing a functional testbed to evaluate and optimize the Brayton cycle as a cost-shared effort with the Indian Institute of Science. The project also investigated developing a novel helical receiver to heat the CO2. Extensive computational modeling of the thermal flow and gradients was conducted to develop the novel CO2 cycle. The program also pursued developing low-cost mirrors, absorbers, and troughs for Rankine cycle solar thermal parabolic trough technology. A new small-scale, positive-displacement organic Rankine cycle expander was developed and tested. Solution-based approaches were considered that promise low-cost manufacturing. Coupled with the heat-collection work were investigations of thermal storage approaches. Specifically, new molten salts were developed capable of much higher-temperature performance with improved thermal conductivity, and a new system was developed for low-temperature Rankine systems.

Improved Performance of Mehsana Cookstove Through Minimal Design Modifications

Abstract: Despite the evolution in cooking practices over the globe, a large population still relies on traditional cooking practices, such as wood-fired cookstoves or “chullahs”. Though the fuel is locally available, the collection of wood is time consuming and tiring. An increase in the efficiency of the “chullahs” reduces the wood consumption and saves the effort of wood collection. Various techniques have been introduced in order to reduce the amount of fuel by improving the thermal performance of the “chullah”. It is experienced that the minimally retrofitted traditional “chullahs” have better acceptance among the users than the ones which are completely differently designed. The objective of the present work is to test one such traditional chullah and investigate the scope of improvement of thermal performance with minimal modifications in the actual stove or in the cooking practice. To achieve that goal, a traditional cookstove from the Kaiyal village of Kadi block from the Mehsana district of Gujarat is selected. Experiments are performed in order to identify the sources of heat loss and to find out the best modification. Water boiling test is carried out for the measurement of thermal performance. The efficiency is found to increase by 37.18% as compared to the original cookstove with an increase in the base height and insertion of twisted tapes.

A Simple Flowmeter for Fluids at High Temperature

Abstract: High temperature and corrosion are the challenging obstacles for any device to be used for molten salt flow measurement. Existing flow measuring devices have limitations due to operating temperatures above 550 ℃, corrosion, maintenance, and high cost. We have introduced a simple and economical method of high-temperature flow measurement which involves measuring the time interval between changes in temperature of successive K-type thermocouples. The device is calibrated using cold and hot water, within the selected range of temperature 30–80 ℃, and the non-dimensional thermophysical properties of molten salt and water are nearly matched. The results obtained show the device is capable of measuring the flow rates with less than 10% error.