Process & Instrumentation

Phase Change Processes of Water ? compressed liquid or subcooled liquid ? The meaning of compressed liquid or subcooled liquid is water exists in liquid phase, or it is not about to vaporize . saturated liquid ? If any heat is transferred to water, until it reaches 100oC ( P = 1 atm), at this point water is still in liquid phase, but any heat addition is transferred to ­­­water will cause some of the liquid to vaporize . A liquid that is about to vaporize is called a saturated liquid saturated vapor ? As we continue transferring heat, the vaporization process continues until the last drop of liquid is vaporized. At this point, the entire liquid is turn into vapor. Any heat loss from this vapor will cause some of the vapor to condense . A vapor that is about to condense is called a saturated vapor. saturated mixture ? This condition exists when vaporization proceed, the liquid and vapor phases coexist in equilibrium . superheated vapor ? if

The First Law of Thermodynamics ? The first law of thermodynamics, also known as the conservation of energy principle, provides a basis for studying the relationships among the various forms of energy and energy interactions. The first law of thermodynamics states that energy can be neither created nor destroyed during a process, it can only change forms . Therefore, every bit of energy should be accounted for during a process. Implicit in the first law statement is the conservation of energy . The conservation of energy principle can be expressed as follows: The net change in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process. That is,   This relation is often referred to as the energy balance and is applicable to any kind of system undergoing any kind of process. Also, energy can

Pressure ? Pressure is defined as a normal force exerted by a fluid per unit area . We speak of pressure when we deal with a fluid or gas . The counterpart of pressure in a solid is normal stress . The actual pressure at spesific point is called absolute pressure , it is measured relative to absolute zero pressure. Unfortunately, most pressure measuring device is calibrated to read zero pressure in atmospheric pressure , so they indicate the difference between the absulte pressure and the atmospheric pressure. The difference is called the gage pressure . The pressure below atmospheric pressure is called vacuum pressure.

Temperature ? Zeroth Law of Thermodynamic ? How do you visualize the temperature is ? Temperature is assosiated with the translation, rotation, vibration, and electronic states of the atoms and molecules that comprises matter. The more active the atoms and molecules the higher the temperature. It is like … mmm when you’re more active, like when you’re running, you feel like your body is warmer right ? you know that your body temperature is higher than before, this is happen because the atoms and molecules that comprises your body is more active. That is, when a object is brought into contact with another body that is at a different temperature, heat is transferred from the body at higher temperature to the one at lower temperature until both bodies attain the same temperature . At that point, the heat transfer stops, and the two bodies are said to have reached thermal equilibrium . The equality of temperature is the only requirement for thermal equilib

System ? Surrounding ? Boundary ? ­                          The first thing we should know as process engineer is what is the system ?             So, the system is part of the universe that we will study or we interested to study about it, and the part of universe outside the system is the surrounding . The real or imaginary surface separates the system from the surrounding is the boundary . The boundary of system can be moveable or fixed. (Note : the boundary is the contact surface shared by both the system and the boundary.) The system may be considered closed or isolated or open system. The closed system or control mass consists of fixed amount of mass, and no mass can cross its boundary, but the energy can cross its boundary. Different from closed system, the isolated system is special case that no mass and energy can cross its boundary. The open system or control volume is a selected region of the universe, either mass or energy can cross its b