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Management decision making based on Markov reward models for refrigeration system

Frenkel I., Khvatskin L., Lisnianski A.

Journal of Polish Safety and Reliability Association

2010

Vol. 1, No. 1

89--98

This paper presents a method for calculation the reliability measures of multi-state supermarket refrigeration system for decision making of system structure, where the system and its components can have different performance levels ranging from perfect functioning to complete failure. The suggested approach presents the Markov reward models for computation of average availability, total number of system’s elements failures and mean time to system failure for multi-state system. Corresponding procedures for reward matrix definition is suggested. A numerical example is presented in order to illustrate the approach.

Cost - effective maintenance with preventive replacement of oldest components

Frenkel I., Khvatskin L.

Eksploatacja i Niezawodność

2006

nr 2

37-39

We consider preventive maintenance of a continuously operating system, whose real-life prototype is a rotating chemical reactor for production of phosphorous acid. The drum, in which the reaction takes place, has 42 rollers (elements), which are subjected to a heavy load and to chemical corrosion. The components are organized in a ring-type structure. The system failure is defined either as the failure of 2 adjacent elements, or as a failure of any three elements in a set of 6 adjacent elements. The existing servicing policy prescribes replacing only the failed elements at the instant of system failure occurrence. The operational conditions permit the opportunistic replacement of non-failed components at the instant of system failure. In this paper, we propose a cost-effective policy of preventive maintenance: at the same time the system fails, several of the oldest non-failed components are replaced by new ones. The application of the above optimal preventive maintenance policy results in a reduction of the average cost per unit time by 15-30%.