How does heat exchanger effectiveness change with heat capacity ratio?

Effectiveness of heat exchanger decreases as capacity ratio increases. Maximum heat transfer occurs when capacity ratio is unity and therefore ε*Cr curves given as a function of NTU (number of transfer units) for Cr = 1 for various heat exchanger types.

Under what conditions is the effectiveness NTU method preferred over lmtd method as a method of analysis of a heat exchanger?

In heat exchanger analysis, if the fluid inlet and outlet temperatures are specified or can be determined by simple energy balance, the LMTD method can be used; but when these temperatures are not available The NTU or The Effectiveness method is used.

How does heat capacity affect heat transfer?

Heat capacity is the ability of a material to store heat, higher the heat capacity higher the amount to heat stored by the material. Heat transfer usually varies inversely with heat capacity, i.e heat transfer will decrease with increase in heat capacity and vice versa.

What is heat capacity in heat transfer?

The heat capacity rate is heat transfer terminology used in thermodynamics and different forms of engineering denoting the quantity of heat a flowing fluid of a certain mass flow rate is able to absorb or release per unit temperature change per unit time.

What is capacity ratio and how does it helpful during the analysis of a heat transfer process?

Heat and Mass Transfer 2(2+0) Capacity ratio (C): It is defined as ratio of minimum to maximum capacity rate of fluids being used in a heat exchanger. The fluid with lower heat capacity rate will undergo greater change in temperature as compared to fluid with higher heat capacity rate.

Why NTU method is used instead of LMTD?

The LMTD method is convenient for determining the overall heat transfer coefficient based on the measured inlet and outlet fluid temperatures. The ε-NTU method is more convenient for prediction of the outlet fluid temperatures if the heat transfer coefficient and the inlet temperatures are known.

What affects the transfer of heat?

The rate at which an object transfers energy by heating depends on: the surface area, volume and material of the object and the nature of the surface with which the object is in contact. The bigger the temperature difference between a body and its surroundings, the faster the rate at which heat is transferred.