Reducing Operating Costs with Optimal Maintenance Scheduling

The potential benefits of optimal service scheduling for cleaning heat exchangers based on minimizing operating costs are explored. A demonstration is performed on a simulated 20 ton air-to-air vapor compression air conditioner. The costs of regular service schedules (indicative of current practice), minimal schedules needed to maintain comfort, and the optimal schedules are compared. Generally, the minimum comfort schedules have costs between the regular and optimal schedules. The comfort schedules cost as much as 4.2% more than the optimal, the difference increasing with increasing fouling time. Regular (annual) service was as much ·as 11.7% more expensive than optimal for the range of conditions tested. Results are shown for evaporator and condenser fouling and for two different cooling capacity to building load ratios.