Basic Refrigeration Cycle with chiller and AC

Basic Refrigeration Cycle

Basic Refrigeration Cycle with chiller and AC:-

all right let’s take a look at this basic refrigeration cycle of our mechanical.  refrigeration will have four basic components compressor, condenser, evaporator, and expansion. the compressor creates the high and low sides of the system and moves refrigerant through the system. the condenser rejects heat. metering device(expansion) acts as a dividing point in the system creating the high and low pressure sides. the evaporator absorbs heat from the medium to be cooled refrigerant. the compressor as a highly superheated vapor, it immediately begins to reject heat until it condenses in the condenser. it rejects heat condenses into a liquid and then takes on subcooling and enters the metering device(expansion) as a subcooled liquid. it leaves the metering device (expansion) as 75% liquid and 25% vapor. It enters the evaporator absorbs heat and boils to a vapor. it leaves the evaporator as a cold superheated vapor. then it enters the compressor as a superheated vapor absorbs heat from the motor windings is compressed by the piston and again enters the discharge line to go through the refrigeration cycle. again refrigerant leaves the compressor as a highly superheated gas it immediately begins to reject sensible heat and then the condenser continues to reject heat. they reject sensible heat and then about the midpoint in the condenser some of the refrigerant vapor begins to condense into a liquid at this point. it is rejecting latent heat. latent heat is heat that’s rejected during the change of state near the end of the condenser. we have a 100% liquid and it rejects sensible heat as it leaves the condenser. we can measure this sensible heat and tell how much sensible heat. we have rejected by taking a sub-cooling of reading.

the refrigerant enters the metering device as a sub-cooled liquid it leaves the metering device as a 75% liquid and a 25% vapor. it immediately begins to bowl, it boils rejecting latent heat. this is the heat that’s rejected during the change of state and it absorbs heating. it absorbs heat and begins to become less liquid and then at a point approximately 90 percent of the way through the evaporator. it begins to become a pure vapor it now begins to take on super heat. that is a sensible heat above the evaporation point. it leaves the evaporator as a superheated vapor enters the compressor shell. it absorbs heat from the motor windings it absorbs heat from the crank the piston the metal parts inside of the compressor. then only on the downstroke, this superheated vapor is drawn into the piston cylinder and on the upstroke, it absorbs the heat of compression. the heat of compression is it squeezes the molecules so tight that the friction generates heat and it leaves through the discharge valve as a highly superheated vapor now. let’s add some numbers to this before I can add some numbers to this process.

we have to determine what type of refrigerant.  we have the outdoor and indoor ambient temperatures and the seer rating of the piece of refrigeration equipment. we’re working with in this example I want to use r22 with an outdoor temperature of 95 degrees Fahrenheit, and an indoor temperature of 75 degrees Fahrenheit at fifty-five percent relative humidity and we’re going to be using a 10 seer efficiency rating so let’s start back up here again on a 95-degree day refrigerant would be leaving our compressor at approximately 210 degrees Fahrenheit. it immediately begins to reject heat it leaves the compressor. through the discharge line and enters the top of the condenser all along the way it’s rejecting sensible heat. see there’s no change of state taking place it’s a highly superheated vapor it leaves it at 210 degrees and it immediately begins to reject Heat. we have 210 degrees rejecting into a 95 degree. we can readily reject Heat it rejects heat 200 195 190 180 and it continues to reject heat until about halfway through the condenser it rejects heat down to a hundred and twenty-five degrees This is going to be our saturation point this is the point at which some of the refrigerant vapor begins to change into a liquid.  for a  system on a 95 degree, we can determine this number by adding 30 degrees to the outdoor ambient temperature our refrigerant will begin to condense back into a liquid at 125 degrees. this will have a corresponding high side pressure of 278 psi guarantee. that’s a guarantee it’s the pressure-temperature relationship. when we have a change of state taking place, we will have a course top bonding pressure to relate to it so, when I put my gages own if this system is operating correctly my high side gauge on a 95-degree day with a  system would read 278 psi G as we go through the system we now begin to reject latent heat latent heat is heat that is rejected or absorbed during the change of state.

Basic Refrigeration Cycle
Basic Refrigeration Cycle

Although we are rejecting heat the temperature will remain the same as long as the change of states takes place. we’re cooling the refrigerant vapor, it’s changing state, and as long as it’s changing state its temperature and its pressure will remain the same. once we have no more vapor, there’s no more change of state taking place. we can now reject sensible heat. now, if I had attached my gauges and put a thermometer lead here at the exit of the condenser, I might have taken a measured temperature of 105 degrees. I could say that I have 20 degrees sub: 105 subtracted from 125 gives me 20 degrees of subcooling. this is an indication of just how much refrigerant is in the system at 20 degrees of sub-cooling. it is a normal amount of sub-cooling for this type of system it enters the fixed bore metering device. there are a couple of different types of metering devices that are used the one in this example is a fixed bore metering device it’s nothing more than a piston or a tiny hole we often refer to it as an orifice. it’s a very tiny hole a little bit smaller around than a pencil lid. it enters one side of this metering device is a hundred-and-five-degree pure liquid. when it leaves the metering device it immediately flashes to a 25 percent vapor and a 75 percent liquid that’s because the pressure immediately changes the metering device acts as a dividing point in the system creating the high-pressure side and the low-pressure side with a 75-degree indoor temperature. I can subtract 35 degrees and that will give me a 40-degree operating temperature. all the refrigerant is boiling at 40 degrees Fahrenheit and I know it’s going to boil at 40 degrees Fahrenheit. because, if I attach my low side gage I would see that it’s operating at approximately 70 psi G .it’s a guarantee r22 at 70 psi G will allow the refrigerant to boil at 40 degrees Fahrenheit it immediately flash to vapor and begin to ball absorbing heat from the conditioned area the refrigerant is boiling. it’s absorbing latent heat because as the change of state takes place it absorbs the heat but there’s no change in the temperature .it boils boils boils and along about 90% of the way through the evaporator, all of the liquid has the ball to a vapor. we have a pure vapor leaving and from here to the exit of the evaporator it begins to take on superheat in the temperature. it’s sensible heat that is gained above the boiling point. if I come to the end of my vibrator and I attach a thermometer. a digital thermometer lead and it reached 52 degrees Fahrenheit. I would subtract 40 from the 52 which gives me 12 degrees of superheat.  if I have 12 degrees of superheat that means there’s no liquid left in this line to boil to a vapor refrigeration.

because this piston-driven compressor cannot compress a liquid. it has to compress a vapor. can’t compress a liquid you try to compress a liquid all kinds of bad things happen on a compressor. it might break a valve or bust the crank so let’s go through this again when the refrigerant leaves the compressor is a 210-degree highly superheated vapor. it rejects sensible heat. sensible heat it goes from 210 degrees down to 200 190 180 175 160 this is all sensible heat that’s being rejected because we have no change of state taking place once we get down to 125 degrees. we now begin to see some of the highly superheated vapor change into droplets of liquid refrigerant at this point it begins to reject latent heat. the latent heat is rejected the temperature does not change. it’s 125 degrees all along the way change of state taking place at 278 PSIG the refrigerant will condense back into a liquid at 125 degrees and its temperature will not change. we’re rejecting BTUs but there’s no change in the measured temperature once we are about 90% of the way through the condenser. there’s no more vapor left to reject or no more vapor left to condense into a liquid. we have a pure liquid it now begins to reject sensible heat. this is heat that we can measure with a thermometer it rejects heat and we’re going from 125 down to 120 115 110 105 it leaves the condenser as a sub-cooled liquid at 105 degrees it enters the metering device as a pure liquid it leaves the metering device and immediately flashes to a 25% vapor because of the change in pressure it absorbs heat. it absorbs heat all of this is latent heat.  It absorbs heat it boils it boils it boils it balls to a vapor and approximately 90% of the way through our evaporator it becomes a pure vapor at this point. it absorbs sensible heat so now we’re going from 40 degrees to 42 43 44 45 50 it leaves the evaporator at 52 degrees. we subtract our boiling temperature from our measured line temperature of 52 degrees Fahrenheit and that gives us 12 degrees. we can say that we have 12 degrees of superheat. it travels down the suction line and enters the compressor as a superheated vapor. it absorbs heat from the components within the compressor on the down stroke of the piston. it is drawn in through the suction valve into my piston cylinder and on the upstroke. it squeezes the refrigerant vapor so tight. that it creates heat of compression from the friction of the molecules rubbing against themselves. it leaves this cylinder as a highly superheated vapor and begins the refrigeration cycle once again and hopefully your air conditioner or heat pump.

so once again this is the basic refrigeration cycle the most basic refrigeration cycle I can give you is one that applies to a simple air conditioner but keep in mind these four basic components the compressor condenser metering device evaporator can be applied to any mechanical refrigeration from the smallest window unit to the largest chiller system your refrigerator at home has a compressor, a condenser, a metering device, and an evaporator. your wonder unit that hangs out the 1w has to cool. it off as a compressor or condenser. a metering device and an evaporator

your heat pump has a compressor condenser metering device evaporator a dehumidifier a compressor condenser metering device and an evaporator. the largest chiller system sitting on the roof of the largest factory downtown a 300-ton chiller will have a compressor a condenser a metering device and an evaporator.

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