Presentation about The Evaporator
Transcript of Presentation about The Evaporator
THE EVAPORATOR
Hari Sasongko L
Moh. Agung Maulana
Bayu Prakosa
Agung Hadi Susanto
Raditya Dhamas Septyan
Okta Pariantoro
Bayu Wisnu
Reza Candra Buana
What is The Evaporator ?
Evaporator may be defined as a device which is used for absorbing heat from the refrigrated space into refrigeration system.
Type of Evaporator
Dry or Direct expansion evaporator
This type of evaporator is designed with tube where each of the end of that tube is directly connected to the others component.
Flooded Evaporator
Provide for the recirculation of liquid refrigerant by the addition of separation chamber.
Flooded Evaporator (cont)
Controlling the liquid refrigerant level and recirculating the unevaporated liquid refrigerant assure that virtually all the inside suface of the evaporator is in contact with liquid refrigerant under any load.
Evaporator Style
Forced Convection EvaporatorThis evaporator works by blowing the air from the refrigerated space into evaporator system. Which mean, the mechanism of heat transfer in this process is forced convection because of using blower to blowing the air.
Natural Convection Evaporator
Refrigerant is evaporated by the air which flow naturally caused by only gravity. Flow naturally means air is flowing without any force from any devices.
How The Evaporator Works ?
Heat from air inside the space being refrigerated absorbed by the metal of the outside evaporator tube. (convection)
1st
Heat is transfered through the thickness of the metal tube. (conduction)
2nd
Heat from the metal of the inside evaporation tube absorbed by refrigerant inside the tube. (convection)
3rd
Evaporator Design Factor
Pressure drop of flowing refrigerant inside the tube
1st
When pressure drop exists, density of refrigerant gas decrease, which mean weight of refrigerant gas which will pumped by compressor decrease. It means that work of compressor will be decrease. So, cooling capacity will be decrease too.
To prevent pressure drop, the lenght of tubing in evaporator must be kept minimum. For the actual instalation, there is multy circuit tubing.
2nd
Refrigerant velocity of flowing refrigerant inside the tube
If the engineer designs an evaporator with too large diameter tubing, velocity of flowing refrigerant inside the tube will become low. When refrigerant velocity decrease, not all refrigerant will fill the volume of the tube. So, heat transfer will be decrease.
What is Evaporator Frosting ?
Evaporator Frosting is existing of freezy condensate on the outside surface of the evaporator.
How The Evaporator is Frosting ?
1. Evaporator cool air below the condensation temperature.
2. Air change phase become condensate.
3. Condensate cooled to the freezing temperature.
4. Condensate change phase become frost.
How to defrost the evaporator ?
Allowing fan at evaporator to operate while the compressor is shutting down until the evaporator temperature rises a few degrees above 0 OC (melting temperature of frost).
Also, by supplying addition heat to melt the frost.
“Given up is absolutely easy, but it’s not about us”
(Menyerah itu mudah, tetapi itu bukan kita)
Courtesy :Novianto A. P. Rochman
REQUIRED SPECIFICATIONAIR CONDITIONER
CAPACITY : 10 TR T(indoor) : 25 °C T (outdoor) : 30 °C Relative Humidity : 50 %
HFC 134-a Condenser Temp : 50 °C Evaporator Temp : -15 °C Concretes 10x10x5 (meter) L : 0,15 m K : 0,79 W/m °C A : 400 m²
1. Thermal Resistance
2. Heat Transfer
3. Specific heat
4.Heat transfer & mass flow of refrigerant