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Outcomes of Lecture Refrigeration and Air Conditioning? Applications? Basics of Thermodynamics & Heat Transfer? Carnot Cycle

Refrigeration Refrigeration can be defined as the process of removing heat from a substance under controlled conditions. The process of reducing and maintaining the temperature of a body below the temperature of its surroundings.

Refrigeration Refrigeration is the action of cooling and in practice this requires removal of heat (continuous extraction of heat) and discarding it at a higher temperature. The process of keeping an item below room temperature by storing the item in a system or substance designed to cool or freeze. The most common form of refrigeration is provided by systems (i.e. refrigerators) that use a refrigerant chemical to remove heat from items stored inside the system.

Refrigerant A refrigerant is a substance or mixture, usually a fluid which provides cooling effect in refrigeration system. a substance used for refrigeration. a substance used for cooling purpose. Most refrigerants used for air conditioning contribute to global warming, and many also deplete the ozone layer. CFCs (Old R-12 ), HCFCs (Old R-22 ) are potent greenhouse gases when leaked to the atmosphere

Air Conditioning Air Conditioning deals with the study of conditioning of air i.e supplying and maintaining desirable internal atmospheric conditions for human comfort, irrespective of external conditions. Process of treating air so as to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the environmental requirements of the conditioned space. Air Conditioning therefore includes the entire heating.

Air Conditioning

Applications of air conditioning and Refrigeration systems: Residential air conditioning. Industrial Air conditioning. Air conditioning of vehicles. Food storage and distribution. Food processing. Chemical and process industries. Special applications such as in manufacturing industries.

Basic Definitions Heat Transfer Modes of Heat Transfer Conduction Convection Radiation

Difference between Heat Engine, Refrigerator and Heat Pump Heat Engine is a system that converts heat or thermal energy and chemical energy to mechanical energy, which can then be used to do mechanical work. In a heat engine, the energy is transferred from a higher temperature (source) to a lower temperature level (sink). During the process, get the output as work.

Difference between Heat Engine, Refrigerator and Heat Pump A refrigerator is a reversed heat engine which cools and maintains the temperature of a body lower than the atmospheric temperature.

Difference between Heat Engine, Refrigerator and Heat Pump There is no difference between a heat pump and a refrigerator in the case of its cycle of operation. The main difference between the heat pump and refrigerator is its operating temperatures. The working temperatures of a refrigerator are cold temperature T1 and atmospheric temperature Ta. Where as in the case of a heat pump, the working temperatures are atmospheric temperature and hot body temperature T2.

Carnot Cycle The Carnot cycle , is a thermodynamic process, that describes how a fluid is used to convert thermal energy into work.

Carnot Cycle & Reversed Carnot Cycle 1-2 Reversible Isothermal Expansion 2-3 Reversible Adiabatic Expansion 3-4 Reversible Isothermal Compression 4-1 Reversible Adiabatic Compression Reversed Carnot Cycle Adiabatic/ Isentropic: The engine is perfect insulated so that no heat is lost and absorbed. Isothermal: Heat absorbed and rejected at constant temperature http://www.electrical4u.com/carnot-cycle-and-reversed-carnot-cycle/

Characteristics of Carnot Cycle High Efficiency Multi-Source Engine Better reliability and easier maintenance Reversible Safe, discrete and oxygen-free Flexibility

Efficiency of Carnot Cycle The thermal efficiency of any engine working between the temperatures of T1 and T2 is: i.e. increase the temperature difference under which the engine works.