How to save energy ?

[Giannis]

How can we save energy in big cold rooms ?
(we use *****, SemiHermetic Compressors, electrical defrost and air condensers)

[Pooh]

Have you got air locks on the doors or a refrigerated loading dock, these are a good start. Also if possible try to reduce your condensing temperatures, not always easy and not straight forward with mechanical expansion valves but worth the effort. Also you could try electronic expansion valves these give you better superheat control and thus allow the evaporators to operate more efficiently and as an extra bonus allow the condensing temperature to be lowered even more.

Ian

[Andy]

How can we save energy in big cold rooms ?
(we use *****, SemiHermetic Compressors, electrical defrost and air condensers)

Hi Giannis

1/ Use ammonia

2/ Use hot gas defrost

3/ Use compound reciprocating compressors or booster plant.


Or stick to ***** and do the following

1/ Larger condensor and evaporator surface areas and small td's

2/ Liquid sub cooling coils in the condenser

3/ Hot gas defrost

4/ select the compressor with the best COP at the design operating conditions. (don't forget winter and summer)

5/ Electronic expansion valves

6/ Low operating head pressures

7/ Inverter drives on the compressors to match the duty to load.

Hope this helps.

Kind Regards Andy

[The Viking]

Allow the temperature to rise a couple of degrees..

[nike123]

Don't forget to invest in better insulation, better planing of loading and unloading goods in plant, Better air curtains.....
Ups, that is duty's of plant owner, but, you could always advice him.

[Springbok]

Good point about the electronic expansion valves,they are the way of the future.Switching to hotgas could work,or try off cycle defrost systems,depending on the temperatures of the rooms,I've seen cold rooms work efficiently on that.Being in Greece,to achieve low condensing temperatures in those ambient temps can be tricky,but a start....enjoy...

[US Iceman]

How can we save energy in big cold rooms ?
(we use *****, SemiHermetic Compressors, electrical defrost and air condensers)

Since you are basing your question on the above I would recommend this...

Use balanced port expansion valves with the valves correctly adjusted to control the minimum superheat required. If the superheat at the compressors is too high this can cause a reduction in compressor capacity.

Adjust the controls so that the discharge pressure can be lowered during any cooler ambient dry bulb temperature. Lower discharge pressures improve the COP and decrease energy use.

If you have rack systems the controllers may allow some discreet changes for raising suction pressures a small amount also.

If you were starting with an entirely new system, follow Andy's recommendations.

[Gary]

In general a compressor runs most efficiently when the head pressure is low but not too low, the condenser outlet subcooling is high but not too high, the evaporator superheat is low but not too low, and the suction pressure is high but not too high. Balance is everything.

Are we talking about a rack system or individual systems?

[jirhol]

LPA pumps for transport refrigerant lookslike nicely.

[smpsmp45]

Hi Andy,

Simple answer to a difficult question. I liked that

[wambat]

The answer is to find the solution to capture the moisture before it can affect the space so all of the above are good answers.

[Magoo]

High chiller traffic times , turn everything off. Beats trying to air-condition the neibourhood at clients cost. The actual product temp changes very little, control can be by door open timers.
magoo

[Sergei]

Energy savings is complicated issue. Where to start? For end users I suggest following steps.
1. Improve operation of existing refrigeration plant, based on your knowledge of refrigeration and energy savings. Usually, suction pressure up, condensing pressure down, optimum defrosting(defrost when you have frost on the coil). No capital investment at this step.
2. Ask somebody else to improve operation of your refrigeration plant. No capital investment.
3. Invest in energy saving equipment with shortest payback. Certainly, you need outside help to choose right investment. For example, you can invest $10,000 in liquid pump(payback 6 months) or in condenser fan VFD(payback 3 years). First step should be investment in liquid pump. Ask independent consultant, who doesn't have brand or type equipment preferences.