Search results
Results from the WOW.Com Content Network
Commercial refrigeration. Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature). [1] [2] Refrigeration is an artificial, or human-made, cooling method. [1] [2]
The refrigeration process uses a mixture of two isotopes of helium: helium-3 and helium-4.When cooled below approximately 870 millikelvins, the mixture undergoes spontaneous phase separation to form a 3 He-rich phase (the concentrated phase) and a 3 He-poor phase (the dilute phase).
Adsorption refrigeration has been extensively researched in recent years because the technology is often noiseless, non-corrosive and environmentally friendly. [5] The heat source for adsorption refrigeration can be fossil fuel , biomass fuel , nuclear fission , geothermal energy , waste heat , or solar thermal energy .
Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. [1] A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. [2]
A cascade refrigeration cycle is a multi-stage thermodynamic cycle. An example two-stage process is shown at right. (Bottom on mobile) The cascade cycle is often employed for devices such as ULT freezers. [1] In a cascade refrigeration system, two or more vapor-compression cycles with different refrigerants are used.
For temperatures between 10 and 50 K lead is most suitable. Below 10 K one uses magnetic materials which are specially developed for this application. The so-called coefficient of performance (COP; denoted ξ {\displaystyle \xi } ) of coolers is defined as the ratio between the cooling power Q ˙ L {\displaystyle {\dot {Q}}_{\text{L}}} and the ...
The FBISE was established under the FBISE Act 1975. [2] It is an autonomous body of working under the Ministry of Federal Education and Professional Training. [3] The official website of FBISE was launched on June 7, 2001, and was inaugurated by Mrs. Zobaida Jalal, the Minister for Education [4] The first-ever online result of FBISE was announced on 18 August 2001. [5]
Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current.