HVAC School - For Techs, By Techs

Blends and Midpoint w/ Jim Bergmann


Listen Later

Jim talks about dew point, bubble point, and midpoint in refrigerant blends. He also covers the purpose of each and why MeasureQuick displays midpoint on the gauges.

We've formerly used mostly pure refrigerants. However, as new refrigerant blends come on the scene, we have to deal with glide, which indicates that we have a range of boiling temperatures instead of a fixed boiling point. We have bubble point and dew point, which are when the refrigerant starts to boil and finishes boiling, respectively; you generally use dew point to determine the superheat and bubble point to determine the subcooling. Zeotropic refrigerants have larger glides than near-azeotropic refrigerant blends; azeotropes have no glide at all.

The midpoint is the halfway point between the bubble point and dew point in refrigerant blends. Coil temperature typically corresponds with the midpoint.

To find the midpoint of refrigerant in the condenser coil, add the dew and bubble points and divide the sum by two. The process is a bit trickier on evaporator coils. In the evaporator, you run refrigerant through the metering device and get some flash gas; when the refrigerant undergoes that change, the bubble and dew points change. As a result, the midpoint becomes a bit more weighted towards the dew point (60%).

In MeasureQuick, the temperature-pressure charts go a step above and beyond to give you the superheat, subcooling, and midpoint. The midpoint is the effective temperature of the evaporator coil, which is a critical piece of information in refrigeration systems where food products are at stake. You can also use the midpoint for coil DTD and TD.

Jim and Bryan also discuss:

  • R-410A and near-azeotropic refrigerants
  • Metering devices as reactive components
  • Coil temperature misconceptions and uncertainty
  • Pressure differentials and drops in the system
  • Maintaining food quality in refrigeration
  • MeasureQuick mathematical models and formulas
 

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

...more
View all episodesView all episodes
Download on the App Store

HVAC School - For Techs, By TechsBy Bryan Orr

  • 4.9
  • 4.9
  • 4.9
  • 4.9
  • 4.9

4.9

985 ratings


More shows like HVAC School - For Techs, By Techs

View all
The Ramsey Show by Ramsey Network

The Ramsey Show

38,668 Listeners

The EntreLeadership Podcast by Ramsey Network

The EntreLeadership Podcast

4,328 Listeners

The Contractor Fight with Tom Reber by Tom Reber

The Contractor Fight with Tom Reber

408 Listeners

The Fine Homebuilding Podcast by Fine Homebuilding Magazine

The Fine Homebuilding Podcast

771 Listeners

Zack's Shop Talk by Zack Psioda

Zack's Shop Talk

152 Listeners

Building HVAC Science by Bill Spohn

Building HVAC Science

71 Listeners

The Home Service Expert Podcast by Tommy Mello: $200 Million Founder|Forbes, Inc., Entrepreneur Columnist

The Home Service Expert Podcast

721 Listeners

HVAC Know It All Podcast by Gary McCreadie

HVAC Know It All Podcast

208 Listeners

Hvac Uncensored by Gil Cavey

Hvac Uncensored

112 Listeners

HVAC Tech Tips by CE

HVAC Tech Tips

16 Listeners

AC Service Tech Answers Podcast by Craig Migliaccio

AC Service Tech Answers Podcast

89 Listeners

Waste No Day: A Home Services Motivational Podcast by Brian Burton & Nate Minnich

Waste No Day: A Home Services Motivational Podcast

468 Listeners

The Build Show Podcast by Matt Risinger

The Build Show Podcast

359 Listeners

The Refrigeration Mentor Podcast by Trevor Matthews

The Refrigeration Mentor Podcast

29 Listeners

Did You Know?-The ESCO HVAC Podcast by ESCO Institute

Did You Know?-The ESCO HVAC Podcast

6 Listeners