Heat and Mass Transfer Characteristics of a Finned-Tube Evaporator Under Frosting Conditions

Abstract An experimental study was performed to investigate the heat and mass transfer characteristics of a finned-tube evaporator coil utilized in a domestic refrigerator under frosting conditions. Airside heat transfer coefficient was measured as a function of air temperature, humidity ratio, air velocity, and evaporating temperature. In addition, frost thickness was monitored and measured by visualization tests during frosting operation. Based on the experimental results, the degradation of heat transfer performance due to frost formation was explored as a function of operating parameters. The rate of frost formation on the evaporator increases at relatively high humidity, high airflow rate, low inlet air temperature and low refrigerant temperature. As the frost thickness increases, airflow rate gradually decreases, while the capacity increases at the early stage of frost formation and then significantly drops.

Download Full-text

Heat Transfer on Nanofluid Flow With Homogeneous–Heterogeneous Reactions and Internal Heat Generation

Journal of Heat Transfer ◽

10.1115/1.4028644 ◽

2014 ◽

Vol 136 (12) ◽

Cited By ~ 6

Author(s):

Raj Nandkeolyar ◽

Peri K. Kameswaran ◽

Sachin Shaw ◽

Precious Sibanda

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Heat And Mass Transfer ◽

Heat Generation ◽

Internal Heat ◽

Internal Heat Generation ◽

Heterogeneous Reactions ◽

Transfer Coefficients ◽

Transfer Characteristics ◽

Fluid Properties

We investigated heat and mass transfer on water based nanofluid due to the combined effects of homogeneous–heterogeneous reactions, an external magnetic field and internal heat generation. The flow is generated by the movement of a linearly stretched surface, and the nanofluid contains nanoparticles of copper and gold. Exact solutions of the transformed model equations were obtained in terms of hypergeometric functions. To gain more insights regarding subtle impact of fluid and material parameters on the heat and mass transfer characteristics, and the fluid properties, the equations were further solved numerically using the matlab bvp4c solver. The similarities and differences in the behavior, including the heat and mass transfer characteristics, of the copper–water and gold–water nanofluids with respect to changes in the flow parameters were investigated. Finally, we obtained the numerical values of the skin friction and heat transfer coefficients.

Download Full-text

A Fully Wet and Fully Dry Tiny Circular Fin Method for Heat and Mass Transfer Characteristics for Plain Fin-and-Tube Heat Exchangers Under Dehumidifying Conditions

Journal of Heat Transfer ◽

10.1115/1.2739589 ◽

2006 ◽

Vol 129 (9) ◽

pp. 1256-1267 ◽

Cited By ~ 11

Author(s):

Worachest Pirompugd ◽

Chi-Chuan Wang ◽

Somchai Wongwises

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Heat Exchanger ◽

Heat And Mass Transfer ◽

Heat Exchangers ◽

Heat Transfer Characteristic ◽

Transfer Characteristic ◽

Tube Heat Exchanger ◽

Mass Transfer Characteristic ◽

Transfer Characteristics

This study proposes a new method, namely the “fully wet and fully dry tiny circular fin method,” for analyzing the heat and mass transfer characteristics of plain fin-and-tube heat exchangers under dehumidifying conditions. The present method is developed from the tube-by-tube method proposed in the previous study by the same authors. The analysis of the fin-and-tube heat exchangers is carried out by dividing the heat exchanger into many tiny segments. A tiny segment will be assumed with fully wet or fully dry conditions. This method is capable of handling the plain fin-and-tube heat exchanger under fully wet and partially wet conditions. The heat and mass transfer characteristics are presented in dimensionless terms. The ratio of the heat transfer characteristic to mass transfer characteristic is also studied. Based on the reduced results, it is found that the heat transfer and mass transfer characteristics are insensitive to changes in fin spacing. The influence of the inlet relative humidity on the heat transfer characteristic is rather small. For one and two row configurations, a considerable increase of the mass transfer characteristic is encountered when partially wet conditions take place. The heat transfer characteristic is about the same in fully wet and partially wet conditions provided that the number of tube rows is equal to or greater than four. Correlations are proposed to describe the heat and mass characteristics for the present plain fin configuration.

Download Full-text

Features of heat and mass transfer at drying of ceramic products with overglaze paints

Кераміка наука і життя ◽

10.26909/csl.2.2021.1 ◽

2021 ◽

pp. 7-12

Author(s):

O.M. Nedbailo ◽

O.G. Chernyshyn

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Heat Flux ◽

Heat And Mass Transfer ◽

Heat Flux Density ◽

Heat Dissipation ◽

Mass Transfer Process ◽

Drying Process ◽

Air Velocity ◽

The Heat Transfer Coefficient

The basic results of researches of process of a heat exchange are instanced and parsed at drying glasour ceramic colors. Character of change of importance number of Rebinder is established at drying colors and dependence of intensity of a heat dissipation on velocity of air is spotted. The main results of researches of heat and mass transfer process at drying of overglaze ceramic paints in a stream of drying agent are resulted and analyzed. The nature of the change in the value of the Rebinder number for drying paints is established and the dependence of the heat transfer intensity on the air velocity is determined. Analysis of the temperature coefficient of drying and Rebinder's number determined the directions of heat consumption in the drying process of overglaze ceramic paints. It is established that the heat flux density depends on the temperature and velocity of the coolant and does not depend on the chemical composition of the paints. It is shown that the heat transfer coefficient depends on the velocity of the coolant. Compared with heat transfer during laminar flow around the plate during drying, the intensity of heat transfer increases by 75%.

Download Full-text