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ardi
09-06-2007, 04:12 AM
Hi, I'm student/researcher in refrigeration engineering.
I read about reverse cycle-hotgas defrost system from Kramer (Thermobank system), they use thermal storage to store the heat during refrig cycle (it acts as pre-condenser) and use it to re-evaporate the refrigerant during defrost cycle.
In my opinion, this system have energy efficiency advantage as less heat wasted and no additional energy to defrost. It may have disadvantages as it needs additioal equipment e.g. thermal storage, valves and piping, and also pressure drop consideration.
However, I think the benefit of energy efficiency is worth further investigation (use PCM, system efficiency etc.).
My lack of experiences in real system works, causes me to ask this forum:
Is this system have been widely applied?
if no, are there any technical reason for not applying it?
Are there any other advantage/disadvantages in this system?
Thank you, I hope I can learn more on this forum :)
Ardi

smpsmp45
09-06-2007, 04:14 PM
I know carrier has been using this system even for their truck refer units. But the system is complicated in terms of expansion device & other controls. If I am correct Carrier is using Electronic exp device for this.

Sometimes, without this reverse cycle, only hot gas is let in the evaporators & the liquid formed in the evaporator is then collected back in the receiver. ( again carrier does that)

absrbrtek
10-06-2007, 08:15 AM
There are 1000s of Kramer Thermobanks in the US. First one I serviced was in 1982. A pretty finiky system to setup, but once it's setup properly they work nice.

nh3wizard
11-06-2007, 06:42 PM
There are 1000s of Kramer Thermobanks in the US. First one I serviced was in 1982. A pretty finiky system to setup, but once it's setup properly they work nice.

We have approx. 20 Kramer units installed in Florida, if installed properly they work great!

US Iceman
11-06-2007, 07:06 PM
A pretty finiky system to setup, but once it's setup properly they work nice.


I'll second that. The first ones I saw and worked on go back to the late 60's or 70's.

Capt Steve
11-06-2007, 08:24 PM
I agree, if they are installed correctly they work well. The one reason that I know most do not use them is the long term maintenance required to keep them operating properly.

nh3wizard
11-06-2007, 08:53 PM
I agree, if they are installed correctly they work well. The one reason that I know most do not use them is the long term maintenance required to keep them operating properly.

The facility we have the Kramer units versus a plant of equal size running screws with Nh3 costs twice as much to maintain, not just parts but labor also.:eek:

ardi
14-06-2007, 01:00 PM
I see, so the main problem is system maintenance. For smpsmp45, thanks for your info, I plan to apply it in TRU. I didn't know Carrier have been using it. I hv checked their website and installation drawing but couldn't find the thermal storage and its installation. Could you give the model which use it? or maybe its spec.
Thanks and regards,
ardi