What is the formula for critical radius of insulation?

… the differentiation and solving for r 2 yields the critical radius of insulation for a circular body. The critical radius of insulation is given by the following equationr c = (k/h). Above this critical radius, the heat flux decreases and below it, the heat flux increases as the fig.

What is the critical radius of insulation state formula for the cylinder?

That radius is known as critical radius of insulation. For Cylinder, Rc=K/h. But for electric wires we have to keep the insulation thickness less than 1 cm in order to dissipate more and more amount of heat to the surrounding.

What is the critical radius of insulation in heat transfer?

The critical radius of insulation is a counterintuitive concept within the study of heat transfer. The theory states that adding insulation to a cylindrical or spherical object will increase the rate of heat loss rather than decrease it, if the radius (thickness) of the insulation is at its “critical” value.

What is the critical radius of insulation for a sphere equal to?

What is the value of a critical radius? Explanation: Critical radius of insulation = k/h = 0.0825/8 = 0.01031 m = 10.31 mm. Explanation: It depends on the variation of angle with layers of insulation. Explanation: K for common insulating material is 0.05 W/ m degree.

What is meant by critical radius of insulation What is its significance?

The critical radius of insulation is the thickness of insulation at which the rate of heat transfer through the body is maximum. It means that the rate of heat transfer increases with an increase in the thickness of insulation up to the critical radius of insulation.

What is the critical thickness of insulation for cylinder?

Figure 2 Variation of heat dissipation with radius ratio for a cylindrical system. critical thickness is 6 – 4 = 2 cm. The maximum heat dissipation is given by Eq.

What is critical radius of insulation or critical thickness?

The thickness up to which heat flow increases and after which heat flow decreases is termed as Critical thickness. The insulation radius at which resistance to heat flow is minimum and consequently heat flow rate is maximum is called “critical radius”.

What is critical radius of insulation Mcq?

Critical Thickness of Insulation MCQ Question 10 Detailed Solution. Concept: The critical radius of insulation rc is the radius up to which the addition of material increases the rate of heat loss and after critical radius addition of heat results in a decrease in heat loss.

What happens when the radius of insulation on a pipe exceeds the critical value?

When the thickness of insulation on a pipe exceeds the critical value the heat flow rate. Options are : Increases.

What is critical insulation?

The thickness upto which heat flow increases and after which heat flow decreases is termed as critical thickness. The thicker the insulation, the lower the heat transfer rate. This is due to the fact the outer surface have always the same area.

What is correct formula of Biot number?

The Biot number equals the product of the heat transfer coefficient and the characteristic length divided by thermal conductivity.