Why actual experimental heat transfer coefficient is more than theoretical heat transfer coefficient?

The difference in the value of heat transfer coefficient between the numerical and experimental results is due to assumptions of the numerical simulation and uncertainty of measurement.

Why the heat transfer coefficient in natural convection is less than that of forced convection?

Why heat transfer coefficient for natural convection is much lesser than that of forced convection? (NOV-DEC 13] The convection heat transfer coefficient will usually be higher in forced convection and lower in free convection since heat transfer coefficient depends on the fluid velocity, and free convection involves …

Why there is a difference in heat transfer from top and bottom surface of a horizontal hot plate?

It is considered as a natural convection heat transfer process because the heat transfer from the heated bottom surface to the top surface of the enclosure is done by a series of Benard cells of the air due to density difference caused by temperature difference. …

What factors affect the value of the heat transfer coefficient and how do these factors affect H increase or decrease )?

Heat transfer coefficient depends on both the thermal properties of a medium, the hydrodynamic characteristics of its flow, and the hydrodynamic and thermal boundary conditions.

Is a higher or lower heat transfer coefficient better?

Assuming the heat transfer surface and temperature difference remain unchanged, the greater the U value, the greater the heat transfer rate. In other words, this means that for a certain heat exchanger and product, a higher U value could lead to shorter batch times and increased production/revenue.

What is the difference between co current heat exchanger and counter current heat exchanger?

In the cocurrent mode, both the hot and cold streams enter the heat exchanger at one end, and leave at the opposite end. In the countercurrent mode, the streams enter at opposite ends of the heat exchanger.

What do mean by convection heat transfer what are its different types explain by giving suitable examples?

Convection is the process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. The initial heat transfer between the object and the fluid takes place through conduction, but the bulk heat transfer happens due to the motion of the fluid. It happens in liquids and gases.

What does the heat transfer coefficient describe?

The heat transfer coefficient describes the convective heat transfer from a solid to a flowing fluid and vice versa! The heat transfer coefficient describes the convective heat transfer from a solid to a flowing fluid (gas or liquid) or vice versa. Such a situation can be seen, for example, with a radiator.

What is the convection heat transfer coefficient of a mold?

The convection heat transfer coefficient, h, is a measure of the resistance to heat transfer across a thin near-stagnant fluid layer between the bulk of the fluid and the solid surface. Table 4.2 gives approximate values for the heat transfer coefficient for several fluids that might be used to cool the mold and its molten contents.

What are the effects of free convection on heat transfer?

Depending on the situation, free convection can make a considerable contribution to the total heat transfer. If a fluid flows along a wall, this has an effect on the flow velocity. Due to the frictional forces (described by the viscosity) between wall and fluid and within the fluid, the flow velocity of the fluid is disturbed.

What is the overall heat transfer rate for combined modes?

The overall heat transfer rate for combined modes is usually expressed in terms of an overall conductance or heat transfer coefficient, U. In that case, the heat transfer rate is: The general definition of the heat transfer coefficient is: Δ T: difference in temperature between the solid surface and surrounding fluid area, K