Method for Determining Best Economic Pipe Size for Ammonia Refrigeration Piping
Author: Robert A. Sterling, P.E.
Economic pipe size is an important factor in project design and analysis for any piping system. In the industrial ammonia refrigeration industry, where energy usage by, and maintenance of, the mechanical refrigeration system is often one of the largest operating costs, a flexible method for analysis to minimize the total life-cycle cost of a piping system is desirable.
A method for determining a minimum header life-cycle cost has been developed to meet this need. Through broad-based piping labor and materials data aggregated by RSMeans (a company that aggregates construction cost data), data on energy usage by equipment in ammonia refrigeration systems, and well-established calculations for pressure drop in piping, the method produces a series of results that allow comparison of life-cycle costs for several pipe sizes in the same service. The method is flexible enough to apply over a large range of conditions and pipe sizes and is suitable for incorporating into an automatic software calculation package.