Variable-Speed Motors and Why They Matter w/ Jamie Kitchen (Podcast)

Jamie Kitchen from Danfoss talks all about variable-speed motor technology. He discusses why those motors exist, what they do, and how to think differently about the future of HVAC/R.

Most techs think about variable-speed motors as the X13 and ECM blowers in residential applications. Those motors can adjust their performance based on ambient temperatures and moisture levels. So, variable performance may result in better comfort and efficiency.

ECM motors adjust airflow based on sensor inputs, especially dehumidification calls. The sensors may pick up both sensible and latent heat content. Sensible heat is what we can feel (dry-bulb temperature). Latent heat refers to moisture in the air (humidity, wet-bulb). ECM motors adjust their speed based on data from both, which is highly beneficial for greater comfort in the home. Human comfort is a lot more complex than feeling satisfied with a single number on the thermostat; ECM motors help control humidity and give you more leeway over selecting an acceptable dry-bulb temperature of a space.

Variable-speed motors exist on the commercial side of the HVAC industry as well. Commercial HVAC equipment brings in more fresh air and is overall less restrictive than residential. A variable-speed motor can help manage the latent heat of fresh air and work as a form of air treatment. Variable-speed motors compare indoor and outdoor conditions to treat the fresh air and maintain the indoor conditions. These motors account for sensible and latent heat loads, just like the residential ECM motors, and they adjust themselves constantly.

Jamie and Bryan also discuss:

Capacity and heat profiles
X13 motor controversy
Having multiple variable-speed components in a system (compressor, blower, etc.)
Sensible heat ratio (SHR) and heat load matching
Complex human comfort
Reheat coils
Air treatment requirements

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Author:

Bryan Orr

Company: HVAC School

Position: Founder

Jamie Kitchen

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In this short podcast episode, Bryan talks about the CPS Molecular Transformator and what it does.

The Molecular Transformator is a version of a tube-in-shell heat exchanger, which is a method of exchanging heat from one fluid medium to another fluid medium. Tubes containing a fluid pass through a shell containing water or glycol, and there is a heat exchange between that secondary fluid and the fluid being circulated in the tubes. In a Molecular Transformator, the fluid being circulated is recovered refrigerant, and the secondary fluid is water (in a bucket), which absorbs heat from the refrigerant and cools it down to make sure that the refrigerant enters the recovery tank as a liquid.

Refrigerant recovery machines have condensers inside of them, but they are quite small and don’t hold a lot of refrigerant by design; many recovery machines use microchannel coils. A lot of the time, the refrigerant leaving a recovery machine is a liquid-vapor mix and too high-temperature; a lot of people run a hose over the tank or put it in a bucket of ice. The “Molecular Transformator” tries to settle the vapor molecules down into a liquid; it transforms the vapor molecules using the same mechanism as a tube-in-shell heat exchanger.

The main issue is that there will be leftover refrigerant in the Molecular Transformator after recovery. However, you can mitigate this problem with ball valves and proper purging. Do so responsibly to avoid venting refrigerant.

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