Refrigerators
Summary
- A refrigerator is any kind of enclosure (like a box, cabinet, or room) whose interior temperature is kept substantially lower than the surrounding environment.
- Types of Refrigerators
- non-mechanical
- for example: ice box, root cellar, wine cellar
- are not often considered true refrigerators
- mechanical
- vapor compression
- vapor absorption
- multievaporator, cascade
- gas cycle, air cycle
- pulse tube
- thermoacoustic
- electronic
- thermoelectric
- magnetic, magneto-calorific
- non-mechanical
- An air conditioner is a mechanical system in a room, building, or vehicle for controlling…
- temperature (by providing cool air),
- humidity (by providing dry air),
- and ventilation (by providing fresh air).
- A heat pump is a device for moving heat mechanically.
- A heat pump can move heat against the temperature gradient (from cold to hot).
- Refrigerators and air conditioners are examples of heat pumps.
- In common usage, the tem heat pump often refers to air conditioners that can be run…
- "forward" to cool a building in summer by extracting heat from the building and depositing it in the environment (refrigerating the building and heating the environment) or
- "backward" to warm a building in winter by extracting heat from the environment and depositing it in the building (refrigerating the environment and heating the building).
- Energy is conserved in the operation of a heat pump.
- The heat extracted from the cold reservoir (Qc) plus the work done by the system (W) is equal to the heat deposted in the hot reservoir (Qh).
- The coefficient of performance (COP) is the ratio of the useful energy output of a system to the mechanical work required to operate it.
- The COP is a measure of the effectiveness of a mechanical device or system at performing some task.
- The COP of a heat pump used as…
- an air conditioner or refrigerator is the ratio of the heat extracted to the mechanical work required to operate it.
COP = Qc/W
- a heater is the ratio of the heat deposited in the room to the mechanical work required to operate it.
COP = Qh/W
- an air conditioner or refrigerator is the ratio of the heat extracted to the mechanical work required to operate it.