How to set TXV superheat and other helpful TXV tips | HVACR Distillery Episode 2
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- Опубликовано: 18 сен 2024
- In this episode of the HVACR Distillery, Jamie shares some lesser-known tips on how to install, maintain, and set superheat on a TXV, or Thermostatic Expansion Valve. He also covers what goes inside a bulb sensor, what it does, and how to avoid overloading your compressor.
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Hii sir, your video so helpful ,What is cause of ice frosting on txv and txv outline pipe including Capillary feeding to evaporator.
Even site glass is showing full.
Hey Ravi,
You can easily find the answer in our free Ref Tools app. Download it here: www.danfoss.com/en/service-and-support/downloads/dcs/ref-tools/#tab-overview
Then, once you open the app, find the Troubleshooter under "Tools". Select Low Pressure, then select Air Coolers and scroll to "Evaporator inlet and TXV covered by frost or ice" and find the most relevant cause.
Awesome channel
Thanks, Vahyae!
Great video. Thank you for sharing. Is warming up TXV bulb a good way to test it ?
Thank you for your question. We are checking with our team and will get back to you.
Hello, great video!!
I have a question for the TE5 Valve.
For the case of a secondary system of glycol with plate exchanger, how can a valve react more quickly, which in this case has MOP? or maybe it is not selected correctly.
Hello Ezequiel. Thank you for your question. By react quicker, I assume you mean how quick they open and close in response to a change in load. I am not sure why you require quicker response times but I will assume it is to limit how low the evaporator pressure drop once the compressor starts up. The rate of opening response for a TXV is based on the amount of load as sensed by the value of the refrigerant superheat leaving the evaporator and to a lesser extent, the type of bulb charge that is being used. It is important therefore to make sure that there is a load on the evaporator to drive the valve open when the compressor starts up. Plate heat exchangers have a relatively small internal volume to hold refrigerant compared to traditional heat exchangers so ensuring that there is a load present when the compressor starts is very important as the compressor can quickly empty out a plate heat exchanger resulting in very low evaporator pressures. With a scroll compressor, this is not good.
MOP or Maximum Operating Pressure bulb charges theoretically should not affect the rate of opening unless the evaporator pressure gets too high. However, some MOP charges limit how fast the valve will open and this can result in slower response times. If this is the case, then replacing the MOP valve with a standard bulb charge and using a crankcase pressure regulator instead will allow the TXV to keep up with the compressor and maintain higher evaporator pressures.
Of course this all assumes that the TXV is sized and installed correctly.”
I hope this helps to answer your question.
Jamie Kitchen,
Danfoss Cooling
Please can you explain in a simple way, what are the differents between internal vs external equalising. What are the applications for internal and external. Thanks deeply appreciated.
Hi Draven. I apologize for the delay. Internal equalized txv's can be used when the evaporator has only a single refrigeration circuit in it and does not utilize a refrigerant distributor. These evaporators have a low pressure drop so the pressure under the diaghpram is very similar to what is present throughout the evaporator. In multi circuit evaporators, a refrigerant distributor is used and there is a large pressure drop between the txv outlet and where the sensing bulb is located. In these circuits, an external equalized txv must be used as the pressure at the txv outlet is higher than what is at the sensing bulb. An external equalized txv will take the pressure at the sensing bulb location so the pressure under the diaghpram is the same as where the sensing bulb is located.
How does the txv manufacturer determine which refrigerant will work with which txv?
This is a good point to cover and I apologize that I missed it before. How a txv responds is determined by the balance of forces under the diaphragm and the force produced by the sensing bulb. Each refrigerant has unique pressure - temperature values which must be overcome by the force exerted by the sensing bulb. As such, when determining the bulb charge for R134a/R513 for example, a mixture of R134a and several other gasses is developed for use in the sensing bulb. The other gasses are used to ensure the txv responds in a similar way across a wide operating temperature range. If it is for R448a, then a mixture of R448a and additional gasses are formulated for the sensing bulb.
The other part of the txv that needs to be sized for a specific refrigerant is the superheat spring as it must provide a specific amount of force so that the required amount of superheat is present before the txv will begin to open. How much force is required for this differs among the various refrigerants so R34a will have a different superheat spring than R404a will. I hope this helps!
I am using 55 ton capacity TXV of Emerson, it controls refrigerant flow to two compressors . When two compressors runs together TXV works fine but when one compressors goes off the TXV starts flooding the compressor. Why is that happening? Is there any difference in selecting a TXV to control single compressor vs dual compressors in the same refrigeration circuit. My application is air cooled chiller.
Any support appreciated
Regards
Thanks for your question. We are checking with our experts and will get back to you.
Can you make some video regarding lubrication for variable speed compressors at low speeds. Danfoss solutions.
Company STARCOOL makes Reefer Containers working with Bitzer Octagon Inverter driven compressor . Control is reduced to three solenoid valves. Variable speed compressor and pulsing ON/OFF valves works together to modulate cooling capacity. Time of opening liquid line valve is short mostly. Wonder what condition it creates for TXV if TXV is there at all.
Danfoss
Hi Rafal. Thank you for your query. Yes, we will certainly consider covering lubrication for variable speed compressors in a future episode as it is an important aspect of how fast and/or slow compressors can operate.
Concerning your question, the pulsing on/off valves in the liquid lines sound like you are referring to Pulse Width Modulating EEV’s which are metering devices. If this is the case, then there will be no need for a mechanical TXV for refrigerant metering.
I hope this answers your question.
Jamie Kitchen
Danfoss Cooling
cut out first sir before measure superheat sir?
When subtitle french on theses vidéos please
Thanks for your comment. We will look into this and get back to you soon.
Rgds
Sujan Sainju
Danfoss Cooling
هل يوجد ترجمه باللغه العربيه ...وشكرا
Hi Samer. We'll look into that for you and see if we can provide Arabic subtitles. Thanks for the suggestion! - LL
Pvdeewsz SD pay
Não entendi nada pois ele não fala a minha língua e eu precisava entender misericórdia senhor
Olá, por favor, deixe-nos saber quais perguntas você tem.