Pradyumna Ghosh

PERFORMANCE COMPARISON OF VARIOUS COOLANTS FOR LOUVERED FIN TUBE AUTOMOTIVE RADIATOR

In the present study, screening of various coolants (water, ethylene glycol, propylene glycol, brines, nanofluid and sugarcane juice) for louvered fin automotive radiator has been done based on different energetic and exergetic performance parameters. Effects on radiator size, weight and cost as well as engine efficiency and fuel consumption are discussed as well. Results show that the sugarcane juice seems to be slightly better in terms of both heat transfer and pumping power than water and nanofluid, whereas significantly better than EG and PG. For same heat transfer capacity, the pumping power requirement is minimum and vice-versa with sugarcane juice, followed by nanofluid, water, EG and PG. Study on brines shows an opportunity to use water+25%PG based nanofluids for improvement of performance as well as operating range. Replacement of water or brines by using sugarcane juice and water or water+25%PG based nanofluids will reduce the radiator size, weight and pumping power, which may lead to increase in compactness and overall engine efficiency or reduction in radiator cost and engine fuel consumption. In overall, both sugarcane juice and nanofluid seem to be potential substitutes of water. However, both have some challenges such as long term stabiliy for practical use.

Numerical Prediction of Heat Transfer Characteristics of Nanofluids in a Minichannel Flow

CFD simulation of the heat transfer and pressure drop characteristics of different nanofluids in a minichannel flow has been explained using FLUENT version 6.3.26. Different nanofluids with nanoparticles of Al2O3, CuO, SiO2, and TiO2 have been used in the simulation process. A comparison of the experimental and computational results has been made for the heat transfer and pressure drop characteristics for the case of Al2O3-water nanofluid for the laminar flow. Also, computations have been made by considering Brownian motion as well as without considering Brownian motion of the nanoparticles. After verification of the computational model with the experimental results for Al2O3-water nanofluid, the simulations were performed for the same experimental readings for different nanofluids in the laminar flow regime to find out the heat transfer and pressure drop characteristics.

Combined energy and exergy analysis of a corrugated plate heat exchanger and experimental investigation

This paper presents an experimental investigation on combined energetic and exergetic performance characteristics of a corrugated plate heat exchanger using water. On the basis of experimental data considering heat exchange with ambient, various energetic and exergetic performance parameters have been evaluated and discussed their interrelationship. General relationship between energy effectiveness and exergy efficiency has been established as well. The result shows that the exergetic efficiency increases with the Reynolds number, hot and cold water inlet temperatures. The exergy loss increases with increase in hot side Reynolds number and inlet temperature, and decreases with increase in cold side Reynolds number and inlet temperature. The dimensionless exergy loss increases with increase of friction factor and number of transfer units. Study reveals that the heat loss has significant contribution on irreversibility and both heat capacity ratio and effectiveness affect the exergetic efficiency. Some energy–exergy relationship correlations have been also obtained based on experimental data.

Experimental study of bubble departure characteristics in forced convective subcooled nucleate boiling

ABSTRACT Visualization experiments in upward forced convective nucleate boiling flows were carried out. The bubble growth and collapse have been measured using high-speed photography technique with distilled water under atmospheric pressure. The experiments show that the bubbles depart from nucleating sites shortly after nucleation and slide along the heater surface. The bubbles grow while sliding, attain a maximum size, then lift from the surface sometime during condensation, and quickly vanish in the bulk liquid. Parametric studies show that bubble diameter and departure frequency increases with an increase in heat flux, a decrease in subcooling, and a decrease in mass flux.

Exergetic analysis of plate evaporator using hybrid nanofluids as secondary refrigerant for low-temperature applications

The brine-based hybrid nanofluids are proposed as a secondary refrigerant in counter-flow corrugated plate evaporator for low-temperature applications. Different types of alumina hybrid nanofluids containing different nanoparticles (copper, silver and multi-walled carbon nanotube) in equal volume with the total volume concentration of 0.8% dispersed in different brines have been assessed for certain cooling load. Various exergetic performance parameters-based comparison has been performed with brines and related hybrid nanofluids for milk chilling, ice making and fish freezing applications. Some energy-exergy relationships have been established as well. Exergetic performance decreases with a decrease in application temperature. The maximum reduction in irreversibility and non-dimensional exergy destruction, and maximum increase in irreversibility distribution ratio (IDR) and exergetic efficiency have been obtained for propylene glycol brine-based alumina multi-walled carbon nanotube hybrid nanofluid. The study reveals that the brine-based hybrid nanofluids may be the suitable substitute as a secondary refrigerant.

Energy-Economic Analysis of Plate Evaporator using Brine-based Hybrid Nanofluids as Secondary Refrigerant

Energy and economic analyses of corrugated plate evaporator have been performed in this study by using brine-based hybrid nanofluids as secondary refrigerant for low temperature applications (milk chilling, ice making and fish freezing). Various hybrid nanofluids containing alumina with different nanoparticles (copper, silver and multi walled carbon nanotube) dispersed in ethylene glycol/water, propylene glycol/water, calcium chloride/water and potassium acetate/water brines have been considered. A comparison has been made based on overall heat transfer coefficient, evaporator size (heat transfer area), pump work, COP, annual cost and payback period. The maximum reduction in heat transfer area has been observed for PG brine-based alumina–silver hybrid nanofluid. Whereas, the maximum reduction in pump work and augmentation in COP have been obtained for PG brine-based alumina–MWCNT hybrid nanofluid. EG brine-based Alumina–Cu hybrid nanofluid yields minimum annual cost. Most of the nanofluids (except PG brin...