An ultra-low ammonia charge system for industrial refrigeration

Abstract

Ammonia is a high energy efficiency refrigerant with wide-ranging utilization in industry. It is a natural refrigerant that causes no ozone depletion or global warming. The refrigerated warehouse industry has been dealing with a difficult and growing challenge due to thousands of pounds of ammonia contained within their facilities. Since ammonia is toxic and flammable in large concentrations, it is subject to numerous federal, state and local safety regulations. The current work evaluates a distributed ultra-low ammonia charge (ULC) refrigeration package that greatly reduces ammonia quantity in comparison to centralized engine room system typical in existing facilities. Using closed coupled components in a compact refrigeration package, and electronic refrigerant injection control technology, facility ammonia charge is reduced by more than 98%, and worst case release scenario reduced to less than a hundred pounds. This evaluation compares initial costs, energy efficiency, water usage, operating and maintenance costs of ULC configuration against equivalent central engine room baseline. The analysis is based on typical medium sized industrial cold storage warehouse in Sacramento, CA with freezer, cooler and dock areas. The ULC configuration shows 7% reduction in energy (kWh) and 3% reduction in water (Gal) usage. The reduction in energy and water costs, combined with other operational and maintenance related savings show that investment in ULC technology will provide a payback within 3 years. The study demonstrates ULC systems as a promising replacement technology for industrial warehouse refrigeration in terms of overall cost of ownership, human safety and environmental benefits.