Thermocreation

Human do not feel comfort at  high temperatures or extremely low temperatures. The situation of body when it feel comfort with the surrounding conditions like temperature, RH%, air flow etc is called the thermal comfort. This comfort situation is at 27 DBT and 19 WBT.  To provide this thermal comfort condition, Air conditioners are used which supply the air at required temperatures. The schematic of an air conditioner is shown as below: Consider a 1 TR air conditioner with ambient 35 DBT and 24 WBT and indoor design conditions are 27 DBT and 19 WBT . So the inlet air to evaporator is at 27 DBT and 19 WBT. The design conditions are as per below: Outdoor conditions: 35 DBT, 24 WBT Indoor conditions: 27 DBT and 19 WBT Evaporator temperature in: 12 deg C Evaporator temperature out: 15 deg C Condensing temperature: 54 deg C Liquid temperature: 46 deg C (ASHRAE conditions) Now main thing to calculate is required mass flow rate of air (CFM) and air out condi...

As it is prohibited to allow liquid refrigerant to enter into compressor because of non compressible nature of refrigerants which can cause serious damage to the compressor, it is necessary to fully evaporate the refrigerant before entering in to compressor. This can be done by several ways which are listed below: 1. super heating of refrigerant at the outlet of refrigerant by using Thermal expansion valve. (used in air-conditioning). 2. By doing liquid suction heat exchanger (in domestic and commercial refrigerator). 3. By doing capillary suction heat exchanger. (In refrigerators) Let's discussed these one by one. Super heating of refrigerant in the evaporator itself:                                                                The air conditioners are used to provide thermal comfort to human being or machin...

Pressure Enthalpy Chart It is a chart used to explain and analyze refrigeration and air conditioning systems. It consist of pressure on ordinate axis and enthalpy on abscissa.  Before explaining the pressure enthalpy chart(shown in fig) lets discuss about some common terms that will be used. Pressure lines:  Pressure lines originated from vertical axis (y-axis) and are horizontal lines drawn parallel to abscissa (x-axis). (light blue line in fig) Enthalpy lines: Enthalpy lines originated from horizontal axis and are vertical lines drawn parallel to vertical axis(Y-axis). (Red color in fig) Critical point: Critical point separate the saturated liquid and saturated vapor curve. Critical temperature: Critical temperature is the temperature above which the vapor can never be liquefied at any pressure. to liquefied vapor, temperature must be reduced. Critical Pressure:   It is the pressure above which the vapor can never be liquefied at any tempe...