COMPRESSORS
Using maintenance to reduce energy consumption Refrigerant loss is a major cause of direct emissions
Compressors are the most energy-intensive part of the refrigeration process. Reducing the work needed here should be considered an important focus for any refrigeration-based energy saving initiative. The Carbon Trust recommends the following to reduce Maintenance and low-cost saving measures Set the condensing temperature at lowest possible
level. Ask a technician to do this. Once the limit is reached, it may be possible to upgrade control valves or condensing capacity to allow a further reduction. On multi-compressor systems, make sure the
compressor suction pressure is set only as low as is required. Often the winter set point can be higher than in summer. Compressors should be checked regularly.
becomes critically low, energy use can increase by between 11 and 15%. Undercharged systems need to operate for longer in order to achieve the same cooling capacity, and systems that have lost refrigerant are likely to operate at higher suction temperatures. This can cause a reduction temperatures, often leading to oil breakdown and overheating problems that generate acid formation in the compressor.
Investment measures temperature can’t be reduced for system reasons.
Regular inspections or tune- ups can, for example, help prevent refrigerant leaks, overheating, and electrical problems as well as making breakdowns less likely.
costs could be slashed by up to 50% simply by switching from reactive to predictive maintenance.
The most compelling argument for properly implemented maintenance is that it guarantees reliability and therefore peace of mind. Reliability – the ability of equipment to achieve its intended function consistently and dependably without failure or breakdown – is the keystone when it comes to being able to trust the performance of compressors. Compressor maintenance can broadly be split into two sections – that performed by the customer and that performed by a compressor overhauler such as my own company.
Check the compressor for leaks both visually and using leak detection equipment (a clue that there might be a leak some- where in the system is low refrigerating pressure).
Check that suction and discharge pressures are within the standard operating range of the compressor.
Check that the motor’s Amps are within standard operating range.
Inspect contacts and tighten terminals as necessary. Megger-test the compressor to check the compressor’s resistance.
Perform an oil test on the compressor to check for leaks. Replace the oil in the compressor. Record operating pressures, amperages, and voltages and make sure they are within the manufacturer’s recommend- ing operating parameters.
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to provide stable pressure to the expansion valve. ambient temperatures. Speed controllers for one or more compressors. If the cooling load varies across a wide range. The cost of variable speed drives (VSDs) depends on the size or new compressor packs can be bought that include variable speed drives. Consider both options when looking into VSDs. For every degree that temperature lift is reduced, you will save around 4% of the compressor energy for chill temperature systems and 2% for low temperature systems.
FANS
Types of maintenance There are, essentially, four maintenance
other three are planned and preventive. Corrective maintenance involves
restoring defective equipment to a working condition as quickly as possible
breakdowns is classed as a ‘run to failure’ approach. It is reactive and unplanned because remedial work is carried out as and when equipment fails in operation. It will not deliver high performing HVAC equipment and is also expensive in the long term, leading to the depreciation of asset value. Planned preventive maintenance (PPM) is designed to ensure the best possible operation of equipment and
avoid expensive unforeseen equipment failure or shutdowns. Unlike corrective
potential problems before they lead to equipment failure. Corrective – tasks executed to repair a faulty device after it has broken down. Predetermined – tasks completed
according to a calendar schedule or operating time. Predictive – tasks conducted by monitoring the performance of equipment using formulas to project future breakdowns.
Condition-based – tasks performed by monitoring the condition of equipment using real-time sensor measurements to help avert unexpected future failures.
Maintenance that should be conducted by compressor
Replacing suction and discharge valves and valve springs. Swapping out mechanical parts that have worn. Replacing worn bearings or if the bearings have exceeded the manufacturers recommend run hours.
Replacing all piston rings and discharge valves. Checking the tolerance on the crankshaft journal and con- necting rods and replace if out of accepted operating range. Performing a full pressure leak test.
decline in air conditioning performance while energy use and fuel bills steadily increase. That makes a compelling case for
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