DryClean Tech
31-03-2010, 02:13 AM
Replaced fail Copeland Scroll with new Copeland Scroll substituting R22 with R404a. Reason for the retro-fit was to operate air over coil at lower temperature (-10F or lower). Replaced TXV’s, originally had Danfoss TEX2 bodies with #5 and #3 orifices. Local Sporlan Rep cross referenced Danfoss orifices and we assembled replacement Sporlans with the appropriate orifices.
Application Dry Cleaning machine with steam heated vapor laden process air with refrigerated vapor recovery. The process heats up the wetted solvent laden garments with steam heated air circulating in the wheel of the machine over the cold coils where the solvent laden vapor condenses back into a liquid and onto the steam heated coil and around and through the machine again and again until such time the garments are deemed dry and or solvent recovery is completed.
Machine operation with regard to low temp refrigeration typicals is conundrum so to speak IMO. When the machine is drying mode a steam coil is used to heat the air and vapor recovery is provided via evaporative coils. During the second phase of the drying cycle know as cool down steam heat is removed and the process air cools down until such temperature or time is realized. This all occurs in approximately 30 minutes.
Typical air temp during 22 minute dry cycle is 100-110F, 8 minute cool down drops air temp to 45F. FWIW: This machine washes/dry’s 60lbs. of DRY clothes/garments. Works essentiall the same as your home washer and dryer with solvent, yet work is completed in a single machine; insert clothes dry and remove clothes dry, sub-cooled and cleaned.
*Copeland ZF33K4E with 100% on time liquid line Vapor injection via spec’d capillary tube.
*Two air over Evaporative coils and a third is essentially a shell/tube solvent cooler.
*Condenser original shell/tube replaced with brazed plate heat exchanger water cooled via water tower.
*Accumulator added during retro-fit.
*Multiple Liquid Line solenoids in front of each TXV thermostatically controlled via PLC.
*Added Liquid Line solenoid in the event defrost circuit was needed to defrost air over coils.
Fired up the machine; stabilized refrigerant charge, i.e., cleared sight-glass and used P\T chart with TXV’s at factory settings (assumed 8-10F).
I attempted to dial in the super heat on the larger evap coil (3-ton TXV). Started by noting the evap outlet was warm, screwed the TXV CCW in an attempt to flood the coil, and finally realized a cooler evaporative outlet temp but the valve was eventually completely opened up in the CCW direction. This was in the dry cycle…. 72F suction outlet, 25psi LS, 265psi HS, 70F water inlet temp @ Condenser -82F condenser water outlet with 88F at TXV liquid inlet.
SH calculated at 25psi=-30F -30 + 72 = 102F
In the cool down cycle:
-10F suction outlet, 14psi LS, 245psi HS, Water into condenser 70F/water out 82F, liquid line inlet at TXV 66F and compressor suction inlet 6 inches from roto-loc valve @ 10F.
SH calculated at 14psi=-50F -50 - -10 = 40F
I’m know Engineer but speculate the TXV is undersized for the load in play. Since I extrapolated the capacity requirements based on the original Scroll compressor capacity and again cross referenced the original Danfoss orifices\valves it was a crap shoot.
FWIW the cooling potential and or capacity was increased with the new low temp 404A Scroll approximately 24K, the original R22 scroll was rated at 90K.
Parts numbers for compressor(s) and TXV’s can be had tomorrow when I return to the office.
Any thoughts????
Kind Regards,
Michael
Application Dry Cleaning machine with steam heated vapor laden process air with refrigerated vapor recovery. The process heats up the wetted solvent laden garments with steam heated air circulating in the wheel of the machine over the cold coils where the solvent laden vapor condenses back into a liquid and onto the steam heated coil and around and through the machine again and again until such time the garments are deemed dry and or solvent recovery is completed.
Machine operation with regard to low temp refrigeration typicals is conundrum so to speak IMO. When the machine is drying mode a steam coil is used to heat the air and vapor recovery is provided via evaporative coils. During the second phase of the drying cycle know as cool down steam heat is removed and the process air cools down until such temperature or time is realized. This all occurs in approximately 30 minutes.
Typical air temp during 22 minute dry cycle is 100-110F, 8 minute cool down drops air temp to 45F. FWIW: This machine washes/dry’s 60lbs. of DRY clothes/garments. Works essentiall the same as your home washer and dryer with solvent, yet work is completed in a single machine; insert clothes dry and remove clothes dry, sub-cooled and cleaned.
*Copeland ZF33K4E with 100% on time liquid line Vapor injection via spec’d capillary tube.
*Two air over Evaporative coils and a third is essentially a shell/tube solvent cooler.
*Condenser original shell/tube replaced with brazed plate heat exchanger water cooled via water tower.
*Accumulator added during retro-fit.
*Multiple Liquid Line solenoids in front of each TXV thermostatically controlled via PLC.
*Added Liquid Line solenoid in the event defrost circuit was needed to defrost air over coils.
Fired up the machine; stabilized refrigerant charge, i.e., cleared sight-glass and used P\T chart with TXV’s at factory settings (assumed 8-10F).
I attempted to dial in the super heat on the larger evap coil (3-ton TXV). Started by noting the evap outlet was warm, screwed the TXV CCW in an attempt to flood the coil, and finally realized a cooler evaporative outlet temp but the valve was eventually completely opened up in the CCW direction. This was in the dry cycle…. 72F suction outlet, 25psi LS, 265psi HS, 70F water inlet temp @ Condenser -82F condenser water outlet with 88F at TXV liquid inlet.
SH calculated at 25psi=-30F -30 + 72 = 102F
In the cool down cycle:
-10F suction outlet, 14psi LS, 245psi HS, Water into condenser 70F/water out 82F, liquid line inlet at TXV 66F and compressor suction inlet 6 inches from roto-loc valve @ 10F.
SH calculated at 14psi=-50F -50 - -10 = 40F
I’m know Engineer but speculate the TXV is undersized for the load in play. Since I extrapolated the capacity requirements based on the original Scroll compressor capacity and again cross referenced the original Danfoss orifices\valves it was a crap shoot.
FWIW the cooling potential and or capacity was increased with the new low temp 404A Scroll approximately 24K, the original R22 scroll was rated at 90K.
Parts numbers for compressor(s) and TXV’s can be had tomorrow when I return to the office.
Any thoughts????
Kind Regards,
Michael