diljan
01-10-2009, 01:14 PM
Hi Folks,
This is my first post here.
By way of introduction, I am a fridgy by trade but have been out of the industry for about 10 years. My focus has always been Air Conditioning and I have very little experience in the refrigeration side.
I was looking at a small display cabinet containing slices and cakes. Located in a cafe. The evaporator was located at the top and was icing up. The drain tray beneath it was warped in the middle due to ice build up on the tray itself which meant that condensate was dripping into the cabinet rather than the drain. This is easily fixed so no big deal there.
After fitting guages I recorded the following details.
Refrigerant: R22
Head Pressure: 1900kpa (amb. temp. 21degC)
Suction Pressure: 200kpa (cabinet temp 10degC)
I assume the desired cabinet temperature would be 3degC with a 5K TD giving evap. temp of -2degC or 370kpa. I am not sure about the 5K TD. I don't have data for cakes. Are they best kept at a lower humidity than say vegetables.
In either case it seems the suction pressure is too low and the discharge pressure way too high for the ambient. I cleaned the condenser fins and checked the fan blades but could not reduce the high discharge pressure. At 21degC I would expect a condensing temp around 35degC or 1250kpa not 1900kpa.
My thought were either air in the system or a blockage in the capillary or somewhere else on the high side. Being a bit rusty in my technical skills Iam not really sure what the problem could be and how to diagnose it.
I really would appreciate some help from those with more experience and knowledge than I have.
Thanks, Dale.
This is my first post here.
By way of introduction, I am a fridgy by trade but have been out of the industry for about 10 years. My focus has always been Air Conditioning and I have very little experience in the refrigeration side.
I was looking at a small display cabinet containing slices and cakes. Located in a cafe. The evaporator was located at the top and was icing up. The drain tray beneath it was warped in the middle due to ice build up on the tray itself which meant that condensate was dripping into the cabinet rather than the drain. This is easily fixed so no big deal there.
After fitting guages I recorded the following details.
Refrigerant: R22
Head Pressure: 1900kpa (amb. temp. 21degC)
Suction Pressure: 200kpa (cabinet temp 10degC)
I assume the desired cabinet temperature would be 3degC with a 5K TD giving evap. temp of -2degC or 370kpa. I am not sure about the 5K TD. I don't have data for cakes. Are they best kept at a lower humidity than say vegetables.
In either case it seems the suction pressure is too low and the discharge pressure way too high for the ambient. I cleaned the condenser fins and checked the fan blades but could not reduce the high discharge pressure. At 21degC I would expect a condensing temp around 35degC or 1250kpa not 1900kpa.
My thought were either air in the system or a blockage in the capillary or somewhere else on the high side. Being a bit rusty in my technical skills Iam not really sure what the problem could be and how to diagnose it.
I really would appreciate some help from those with more experience and knowledge than I have.
Thanks, Dale.