A non-dimensional number generally associated with natural convection heat transfer is________________?

Related Mcqs:

1. In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by___________________?

   A. convection
   B. radiation
   C. conduction
   D. both convection and conduction
   E. none of the above

2. Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in _________________?

   A. electric heater
   B. steam condenser
   C. melting of ice
   D. refrigerator condenser coils
   E. boiler

3. The concept of overall coefficient of heat transfer is used in case of heat transfer by________________?

   A. conduction
   B. convection
   C. radiation
   D. conduction and convection
   E. convection and radiation

4. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by __________________?

   A. conduction
   B. convection
   C. radiation
   D. conduction and convection
   E. convection and radiation

5. When heat is Transferred by molecular collision, it is referred to as heat transfer by __________________?

   A. conduction
   B. convection
   C. radiation
   D. scattering
   E. convection and radiation

6. When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by ___________________?

   A. conduction
   B. convection
   C. radiation
   D. conduction and convection
   E. convection and radiation

7. In regenerator type heat exchanger, heat transfer takes place by___________________?

   A. direct mixing of hot and cold fluids
   B. a complete separation between hot and cold fluids
   C. flow of hot and cold fluids alternately over a surface
   D. generation of heat again and again
   E. indirect transfer

8. Heat transfer by radiation mainly depends upon___________________?

   A. its temperature
   B. nature of the body
   C. kind and extent of its surface
   D. all of the above
   E. none of the above

9. The unit of overall coefficient of heat transfer is___________________?

   A. kcal/m2
   B. kcal/hr °C
   C. kcal/m2 hr °C
   D. kacl/m hr °C
   E. kcal/m3 hr °C

10. Stefan Boltzmann law is applicable for heat transfer by __________________?

    A. conduction
    B. convection
    C. radiation
    D. conduction and radiation combined
    E. convection and radiation combined