CHICAGO — When concern arose six or seven years ago over the amount of refrigerant in a supermarket system, the industry looked for different ways to create refrigeration other than the traditional direct expansion approach.

Two approaches garnered attention. One created a secondary loop with a familiar refrigerant used in conjunction with a glycol or brine type of product. Another approach called distributed did away with a large mechanical room and located smaller condensing units throughout the store.

At an ASHRAE seminar here titled “Analysis Methods and Field Test Results for Low-TEWI Supermarket Refrigeration Systems,” both of the newer methods came in for review. And while both methods have showed promise, neither seemed ready to immediately replace direct expansion as the methodology of choice.

Four presenters reported on separate research. While they said reducing refrigerant charge is good for the environment, this has to be weighed against questions concerning the energy efficiency and initial costs of secondary loop and distributed technology. For the most part, they said the gap can be narrowed, but that point has not yet been reached.