On Availability Determination for MSS Cold Water Supply System by Lz-Transform: Case Study

This paper presents the application of the Lz-transform method to availability assessment of aging multi-state cold water-supply system for factory, specializes on producing raw materials for the plastics industry. The cooling system consists of 14 elements, combined into five sub-systems: two Pump's sub-systems, Chiller, Backup sub-system and Differential Tap. The performance of the system and the sub-systems is measured by their produced cooling capacity. Differential Tap is aging component with the rate of failures depends on time. Times to failures for the rest of the sub-systems components and times to repairs for all system's components are distributed exponentially. Straightforward Markov method applied to solve this problem will require building of a system model with 98,304 states and solving a corresponding system of multiple differential equations. Lz-transform method, which is used for calculation of the system availability, drastically simplified the solution. Presented approach identifies the critical points in the system and checks whether system's availability meets the accepted standards.