Characteristics of brand new zeotropic refrigerant combines are different than old-fashioned refrigerants, it’s good for can understand a two-line PT chart.
Traditional PT charts number this new saturated refrigerant stress, in the psig, with a column to have temperature on the left side. Single-part refrigerants and azeotropes boil and you may condense at that heat for certain stress. Therefore, one column is required to inform you to show the stress-temperatures matchmaking for all the stage-transform techniques when you look at the a network. (get a hold of Fig. 1)
The newest properties of your own brand new zeotropic blends is quite unique of the traditional refrigerants. Zeotropic blends shift during the constitution for the boiling or condensing process (find Fig. 2) Since the mix alter stage, more of you to component will move into another stage reduced than the other people.
So it house is entitled fractionation. The altering structure of h2o causes the fresh boiling-point temperature in order to shift as well hitch hack. The entire change of temperatures from a single region of the temperature exchanger to the other is called the temperature glide. Zeotropic blends cannot be outlined from the a single tension-temperature dating. The temperature slides can cause some other viewpoints for temperature at the an excellent given tension, depending on how far refrigerant is liquids and exactly how much was vapor. The initial philosophy for examining superheat and you will subcooling may be the avoid factors of your slides or perhaps the tension-heat matchmaking having saturated drinking water and you will saturated vapor.
The brand new soaked drinking water standing is usually referred to as brand new bubble area. Photo a pot off h2o standing on a kitchen stove; because it begins to cook it variations bubbles in the liquids. The new over loaded vapor updates is called the new dew point. Photo an area full of vapor and you will dew falls forming on the the item of furniture. PT maps to your zeotropic combines list a couple columns next to for every heat: one to on the soaked drinking water (ripple point) additionally the other on the saturated vapor (dew point).
A few of the zeotropic blends have quite reasonable slides (from?F in order to 2.5?F). For those blends, the fresh new steam and you can liquids pressures are just broke up of the step one otherwise dos psi. As the huge difference is quite short among them philosophy particular manufacturers’ PT charts will only number that line of these blends. Blends having high glide (greater than 5?F will generally features each other columns indexed.
When checking brand new subcool standing, the newest technician often assess the temperatures of water range, the pressure when this occurs and deduct the newest mentioned heat regarding the fresh new soaked heat after the latest condenser. Towards mix you have a look at over loaded heat beside the stress on the liquids (ripple part) line of your own chart.
For one-part or azeotropic refrigerant, the fresh new performing pressure to your reduced edge of a system can also be be discovered from the cross referencing the desired coil heat with the PT graph. Having higher-glide combines, not, the desired coil weather is the average (otherwise midpoint) temperature of coil.
The issue with a couple-column PT charts is that the requirements from the endpoints out-of the warmth glide try indexed, perhaps not this new midpoint. In cases like this, you must add 1 / 2 of the heat slides to the desired midpoint temperature, following browse the soaked steam column to determine the functioning pressure. (come across Fig step three)
Whether your steam column is understand in person during the desired temperatures, then your stop of evaporator will be the proper temperature, however the rest of the coil would be too cooler. In case the h2o column is used truly, then the start of coil is the best temperatures, but the other countries in the coil might possibly be too warm.
Stress Temperature Chart
Two-column PT maps are just because of use once the antique of those. The charging and you can services strategies are comparable both for unmarried-part refrigerants and you can zeotropic mixes, in addition to formal h2o and you will steam analysis correct with the consequences of your blends’ heat slides.
Keep in mind to keep track of the fresh new phase of mix during the section you are interested: saturated vapor spends the steam (dew point) line and you can saturated liquids spends the new drinking water (bubble area) column.
