ZaxHex
01-10-2012, 11:31 PM
I pretty much want to make sure that all my assumptions about what occurs through the basic refrigeration cycle are fine based on thermodynamic principles.
Q1: A saturated temperature is where our an equal amount of evaporation and condensation can occur. If latent heat is applied to a saturated liquid however, more and more is turned to a vapor. Based on this fact, how can there be an equality when more and more of the liquid turns to vapor and less as a liquid?
Q2: A high pressure/high temperature subcooled liquid at 110F/278 psig enters the expansion valve. When it exits, it is 40F/69 psig. Now, the boiling point for the refrigerant at 69 psig is much lower than 110F. Thus, boiling will occur since 110F is much higher than the boiling point of 40F. However, what I am confused about is two things.
Q2a: How do we know how much of the subcooled refrigerant boils and turns into vapor? In other words, with evaporation/boiling, when does this process stop?
I understand the opposite more clearly in that if we match the vapor pressure with the external pressure, boiling will occur but when thinking about dropping the pressure and the states, I have less of an idea.
To me, if a temperature is really high and boiling occurs due to the external pressure dropping, we would have boiling occur and energy would be lost in the liquid (making it colder) but the pressure might be higher (40F is reached but the corresponding pressure is not 69 psig but rather maybe 100 psig). My reasoning is that there is so much vapor already boiled that no more can be produced within the volume and we reach some sort of equilibrium. In other words, we reach an equilibrium due to a closed container but not the same 40F/69 psig temperature/pressure relationship.
Q3: The high pressure on the high pressure side is due to the compressor's result and the low pressure is a result of the valve correct? It's not like these two parts are set before hand to contain a particular amount of pressure right?
Q1: A saturated temperature is where our an equal amount of evaporation and condensation can occur. If latent heat is applied to a saturated liquid however, more and more is turned to a vapor. Based on this fact, how can there be an equality when more and more of the liquid turns to vapor and less as a liquid?
Q2: A high pressure/high temperature subcooled liquid at 110F/278 psig enters the expansion valve. When it exits, it is 40F/69 psig. Now, the boiling point for the refrigerant at 69 psig is much lower than 110F. Thus, boiling will occur since 110F is much higher than the boiling point of 40F. However, what I am confused about is two things.
Q2a: How do we know how much of the subcooled refrigerant boils and turns into vapor? In other words, with evaporation/boiling, when does this process stop?
I understand the opposite more clearly in that if we match the vapor pressure with the external pressure, boiling will occur but when thinking about dropping the pressure and the states, I have less of an idea.
To me, if a temperature is really high and boiling occurs due to the external pressure dropping, we would have boiling occur and energy would be lost in the liquid (making it colder) but the pressure might be higher (40F is reached but the corresponding pressure is not 69 psig but rather maybe 100 psig). My reasoning is that there is so much vapor already boiled that no more can be produced within the volume and we reach some sort of equilibrium. In other words, we reach an equilibrium due to a closed container but not the same 40F/69 psig temperature/pressure relationship.
Q3: The high pressure on the high pressure side is due to the compressor's result and the low pressure is a result of the valve correct? It's not like these two parts are set before hand to contain a particular amount of pressure right?