Thermofluid Dynamics is a cross-discipline related to heat transfer, thermodynamics, and fluid dynamics with emphasis on the effect of thermal process on fluid flow. It consists of four parts:(1) Thermal Drag. In some cases this may strongly influence flow properties, such as mass flow rate, and heat transfer etc. From its definition and the analytical expression of the thermal drag coefficient, it is possible to predict the pressure drop and the critical heat flux of single phase gas flow and gas-liquid tw...