The document discusses different modes of heat transfer including conduction, convection, and radiation. Conduction involves the transfer of heat between atoms or molecules in direct contact. Convection refers to heat transfer through the movement of fluids like gases and liquids, which can occur naturally or through forced means like fans. Radiation involves the transfer of heat through electromagnetic waves without direct contact between objects.
7. OTHER MODES OF ENERGY
• CHEMICAL ENERGY
• ELECTRICAL ENERGY
• MAGNETIC ENERGY
8. HEAT TRANSFER
• Heat is defined as the energy crossing the boundry of a system due to
temeprature difference between system and surroundings.
• Heat exists only due to the heat transfer.
• For the transfer of heat, there should be temperature difference
between two systems.
9. WORK TRANSFER
• Work is an energy interaction between a system and its surroundings.
• Usually, the energy can cross the boundary of an system in the form
of either heat or work.
10. COMPARISON OF WORK AND HEAT TRANSFER
• Both heat and work are recognized only as they cross the boundaries
of a system. It means , both heat and work are boundary phenomena.
• System posses energy but not heat or work. i.e. heat and work are
transient phenomena
11. • Both heat and work are associated with a process not a state. Unlike
properties, heat or work has no meaning at a state.
• Both heat and work are path functions i.e. their magnitude depend
on the path followed during a process as well as the end states.
12. CONDUCTION
• Conduction is a process in which heat flows in a body is achieved by
the transfer of the momentum of individual atoms or molecules
without mixing.
• Or Transfer of heat from one atom to another within an object by in
direct contact with each other.
• For example, flow of heat through metal shell of a boiler takes place
by conductions as far as solid wall or shell is considered.
13. CONVECTION
• Convection is process in which heat flow is achieved by actual mixing
of warmer portions with cooler portions of same material.
• It is the heat transfer due to bulk movement within fluid such as gases
and liquids.
• For example , heating of water by hot surface is mainly by convection.
• NATURAL CONVECTION refers to a case where the fluid movement is
created by the warm fluid itself. the density of fluid decreases as it is
heated. thus, hot fluids are lighter than cool fluid.
14. • FORCED CONVECTION uses external means of producing fluid
movement.
• Forced convection is what in winter days, heat loss from your body is
increases due to the constant replenishment of cold air by the wind.
• Natural wind and fans are two most common sources of forced
convection.
15. RADIATION
• Radiation is a energy transfer process in which heat flows through
space by means of electromagnetic waves.
• Radiatve heat transfer occurs when the emitted radiation strikes
another body and is absorbed.we all experience radiative heat
transfer everyday; solar radiation, absorbed by our skin, is why we
feel warmer in the sun in the shadow.
16. • Solar water heaters, solar cookers, microwave ovens, microwave
cookers, sonicator baths etc., are a few example in which radiation is
utilized for producing heat.
17. MODES OFF HEAT TRANSER
• PARALLEL HEAT FLOW
• When the hot fluids and the cold fluids enter the apparatus from the
same end , the flow is parallel to each other. this arrangement is
known as parallel flow.
18. • COUNTER HAET FLOW
• When the fluids is passed through one end of the apparatus while
cold fluid is passed through the other end, fluid pass in opposite
direction. This arrangement is known as counter-flow.
