| Evaporators in the Cold Room |
Cold Room Pack Malfunction
Two unit coolers were employed with interlaced coils each unit cooler having 50% of its circuit being served by a single pack in order to provide 100% standby (N+1). At low load conditions and during start up, the packs and controls were seen to be behaving erratically.
Each pack comprised of 2 fixed speed Copeland Compressors and a single digital scroll to provide capacity control. Heat rejection was via Air Cool Condensers located approx 40 meters from the cold room, with a liquid receiver in circuit.
Whilst watching the plant during these low load conditions, it was clear from temperature recorders that the store condition was being lost. Moreover, it was becoming extremely urgent for the installer to get the pack into operation in order to meet the end user client’s critical deadlines for production.
|
| Pack with ClimaCheck Probes and Transducers attached |
ClimaCheck Monitoring / Analysis
Consequently, Mike was called in to assist the engineers in determining the cause of the problem in order to bring about a rapid and satisfactory solution. Following an initial visit by Business Edge Commissioning Manager, Philip Chambers, Mike arranged for a special ClimaCheck template to be created specifically suited to the refrigeration circuitry of this installation.
The refrigeration circuit included oil separation and oil management control to each compressor and an economiser circuit for sub cooling liquid refrigerant entering the main T.E.V.
With ClimaCheck in operation, Mike was able to see the behaviour of absolutely every element of the system including its cooling capacity, C.O.P, evaporating temperature, condensing temperature and the superheat at both the main T.E.V. and the economiser T.E.V. From this he was then able to deduce the cause of the problem, which related to the behaviour of each E.E.V. (Electronic Expansion Valves) at the evaporator’s, coupled with the arrangement of the unit coolers where discharged air from each was being directed and drawn into the inlet of the opposing evaporator causing sporadic E.E.V. control.
The controls were arranged to work off a single sensor and the problem was resolved.
|
