Refrigeration System Overview ASTI 32 Hour Managing Ammonia Course September 27 30, 2016
A refrigeration system is a mechanical heat transport system. The system absorbs heat energy from an area it is not wanted and moves that heat energy to an area where it can be rejected without doing harm. The heat transport is accomplished by evaporating and condensing refrigerant liquid in a repeating cycle of evaporation condensation RULE #1: Heat Energy ALWAYS travels from a hotter area/object to a cooler area/object. Rule #2: The greater the difference in temperature the faster the heat energy will flow.
RULE #1: Heat Energy ALWAYS travels from a hotter area/object to a cooler area/object. Rule #2: The greater the difference in temperature the faster the heat energy will flow. The purpose of a refrigeration system is to maintain a temperature. Here is how: Heat energy enters the system in the EVAPORATOR. Liquid NH3 boils at a controlled pressure which makes the liquid boil at a constant temperature. This region is the LOW SIDE of the system The heat energy is transported by the gas formed by the boiling of the NH3 to the COMPRESSOR where the gas is raised to a higher pressure and temperature by reducing the volume of the gas. This is the HIGH SIDE of the system. The portion of the system coming to the compressor inlet port is the LOW SIDE of the system. The heat energy borne by the gas is transported to the area where it is cooler. This the CONDENSER. The heat energy leaves the system to the ambient conditions and as the energy is released the gas condenses into a warm LIQUID at the higher pressure. The warm, high pressure liquid is transported back to the evaporator. The liquid must pass through a restriction that causes a reduction of pressure and temperature of the liquid. The liquid is now at the right condition to absorb heat. The POINT of EXPANSION separates the High side from the Low side.
EVAPORATORS Where the heat energy enters the system
EVAPORATORS Where the heat energy enters the system
EVAPORATORS Where the heat energy enters the system
EVAPORATORS Where the heat energy enters the system
EVAPORATORS Where the heat energy enters the system
EVAPORATORS Where the heat energy enters the system
Some systems use mechanical pumps to move liquid to the evaporators
Some systems use mechanical pumps to move liquid to the evaporators
Some systems use mechanical pumps to move liquid to the evaporators
COMPRESSORS Where the heat energy borne by the gas is increased by reducing the volume of the gas
COMPRESSORS Where the heat energy borne by the gas is increased by reducing the volume of the gas
CONDENSER Where the heat energy is rejected to the environment
RECEIVER Where the condensed liquid goes when it drains from the condenser
RECEIVER Where the condensed liquid goes when it drains from the condenser Many time have automatic valves to control level and flow to the low side of the system.
The POINT OF EXPANSION Warm high pressure liquid flows from the right cold liquid and gas flow to the left after the expansion valves
THE CYCLE IS COMPLETE 1)EXPANSION 2) EVAPORATION 3) COMPRESSION 4) CONDENSATION HEAT ENERGY ENTERS AND LEAVES THE SYSTEM THE REFRIGERANT STAYS WITHIN THE CLOSED LOOP OF THE SYSTEM. REPEAT, REPEAT, REPEAT..
WHAT IF SOMETHING GOES WRONG?
THE OVER PRESSURE CONTROL STATION CAN BE USED TO MANIPULATE PRESSURE TO KEEP THE NH3 IN THE SYSTEM OR IF NECESSARY SEND THE AMMONIA TO A RELEASE POINT SUCH AS A DIFFUSION TANK OR TO THE ATMOSPHERE
This is an oil pot. The presence of the frost indicates that no oil has accumulated in the vessel.
Compressor inlet The presence of frost does not mean liquid is entering the compressor. It means the temperature of the flowing gas is colder than the surrounding air and water has condensed from the air onto the valve and strainer body.
Liquid transfer vessel: Liquid is where the frost is present. The un frosted portion has NH3 gas there.
Why do we have refrigeration? To provide safe food to the world. THANK YOU TO THE MANAGEMENT AND STAFF OF COASTAL COOLING, LLC CASTROVILLE, CALIFORNIA