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THERMODYNAMICS & RELATED TERMS



THERMODYNAMICS & RELATED TERMS

THERMODYNAMICS IS THE STUDY OF ENERGY INTERACTIONS BETWEEN SYSTEMS AND THE EFFECT OF THESE INTERACTIONS ON THE SYSTEM PROPERTIES. ENERGY TRANSFER BETWEEN SYSTEMS TAKES PLACE IN THE FORM OF HEAT AND/OR WORK. THERMODYNAMICS DEALS WITH SYSTEMS IN EQUILIBRIUM.

A THERMODYNAMIC SYSTEM IS DEFINED AS A QUANTITY OF MATTER OF FIXED MASS AND IDENTITY UPON WHICH ATTENTION IS FOCUSED FOR STUDY. IN SIMPLE TERMS, A SYSTEM IS WHATEVER WE WANT TO STUDY. A SYSTEM COULD BE AS SIMPLE AS A GAS IN A CYLINDER OR AS COMPLEX AS A NUCLEAR POWER PLANT. EVERYTHING EXTERNAL TO THE SYSTEM IS THE SURROUNDINGS. THE SYSTEM IS SEPARATED FROM THE SURROUNDINGS BY THE SYSTEM BOUNDARIES. THERMODYNAMIC SYSTEMS CAN BE FURTHER CLASSIFIED INTO CLOSED SYSTEMS, OPEN SYSTEMS AND ISOLATED SYSTEMS.
A CONTROL VOLUME, WHICH MAY BE CONSIDERED AS AN OPEN SYSTEM, IS DEFINED AS A SPECIFIED REGION IN SPACE UPON WHICH ATTENTION IS FOCUSED. THE CONTROL VOLUME IS SEPARATED FROM THE SURROUNDINGS BY A CONTROL SURFACE. BOTH MASS AND ENERGY CAN ENTER OR LEAVE THE CONTROL VOLUME.

THE FIRST AND AN EXTREMELY IMPORTANT STEP IN THE STUDY OF THERMODYNAMICS IS TO CHOOSE AND IDENTIFY THE SYSTEM PROPERLY AND SHOW THE SYSTEM BOUNDARIES CLEARLY.

A PROCESS IS DEFINED AS THE PATH OF THERMODYNAMIC STATES WHICH THE SYSTEM PASSES THROUGH AS IT GOES FROM AN INITIAL STATE TO A FINAL STATE. 
IN REFRIGERATION AND AIR CONDITIONING ONE ENCOUNTERS A WIDE VARIETY OF PROCESSES. UNDERSTANDING THE NATURE OF THE PROCESS PATH IS VERY IMPORTANT AS HEAT AND WORK DEPEND ON THE PATH.
A SYSTEM IS SAID TO HAVE UNDERGONE A CYCLE IF BEGINNING WITH AN INITIAL STATE IT GOES THROUGH DIFFERENT PROCESSES AND FINALLY ARRIVES AT THE INITIAL STATE.


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