Engine Heat Transfer

·         ____________ is the transfer of heat from one part of a substance to another part of the same substance.

Answer: Conduction is defined as the transfer of heat from one part of a substance to another part of the same substance while convection is defined as the transfer of heat within a fluid by mixing of one portion of fluid with another.

·         ____________ is the transfer of heat within a fluid by mixing of one portion of fluid with another.

Answer: Convection is defined as the transfer of heat within a fluid by mixing of one portion of fluid with another while conduction is defined as the transfer of heat from one part of a substance to another part of the same substance.

·         ____________ convection occurs when the fluid circulates by virtue of the natural differences in densities of hot and cold fluids.

Answer: Natural

·         In natural convection, the denser portions of the fluid move downward because of the greater force of gravity, as compared with the force on the less dense.

Answer: True

·         When the work is done to blow or pump the fluid, it is said to be ____________ convection.

Answer: When the work is done to blow or pump the fluid, it is said to be forced convection while natural convection occurs when the fluid circulates by virtue of the natural differences in densities of hot and cold fluids.

·         ____________ is the transfer of heat through space or matter by means other than conduction or convection.

Answer: Radiation is the transfer of heat through space or matter by means other than conduction or convection and when the work is done to blow or pump the fluid, it is said to be forced convection while natural convection occurs when the fluid circulates by virtue of the natural differences in densities of hot and cold fluids.

·         In case of air cooling, the boundary layer as on the gas side offers great resistance, but the effect of this is compensated largely by providing more surface areas by way of cooling pins.

Answer: Yes, in case of air cooling, the boundary layer as on the gas side offers great resistance, but the effect of this is compensated largely by providing more surface areas by way of cooling pins.

·         In case of water cooling, there no boundary layer of the liquid coolant on the outside of the cylinder wall.

Answer: Actually, in case of water cooling, there is also a boundary layer of the liquid coolant on the outside of the cylinder wall.

·         When the spark advance is same as the optimum value the heat rejected to cooling system is increased.

Answer: In fact, when the spark advance is different from the optimum value the heat rejected to cooling system is increased.

·         Gas temperature remain at a higher average with increased speed.

Answer: True