Storage Type Exchangers Immiscible Fluid Exchanger
In the regenerators, the hot and cold fluids flow alternatively through a solid matrix of high heat capacity. When the hot fluid flows through the matrix in an interval of time, heat is transferred from the fluid to the matrix, which stores it in the form of an increase in its internal energy. This stored energy is then transferred to the cold fluid as it flows through the matrix in the next interval of time. The matrix is then subjected to periodic heating and cooling.
A piece of equipment often needed and encountered in heat transfer practice is the so-called “heat exchanger”. Basically, this is the device, which allows the energy transfer, because of temperature difference, between a hot fluid and a cold fluid. This occurs either across a solid barrier interposes between the two fluids to prevent their mixing, or to and from this solid wall as a result of the alternate passing of hot and cold fluids over the barrier.
In the figure shown below is a schematic picture of such a general heat exchanger .In general, there are also, as shown in figure, other surfaces whose function it is to confine one or both of the fluids and which have essentially no heat transfer across them. In many heat exchangers, the barrier between the fluids will be a tube wall or a plane wall and the other containment barriers might be circular cylindrical surfaces or plan surfaces.
Storage type heat exchangers may have the matrices, which are either (1) stationary or (2) rotating. Figure (3) shows a typical regenerator with a stationary matrix. During the heating period of the cycle when the hot fluid flows through the matrix, valves A and B are kept open and C and D are kept close. During the cooling period, valves A and B are kept close and C and D are kept open. A regenerator with a stationary matrix is used in a Stirling refrigerator, such as Philips refrigerating machine for liquefaction of air, and in a gas turbine power plant.
Types Of Heat Exchangers: –
Heat exchangers can be grouped into the three broad classes:
- Transfer type heat exchangers or recuperators
- Storage type heat exchangers or regenerators
- Direct contact type heat exchangers or mixers