Refrigerant testing heats up
It's always something. Chloroflurocarbon refrigerants were phased out in the 1990s because they damage the ozone layer of the atmosphere and were replaced mainly by hydroflurocarbons. HFCs are safe for the ozone layer, but they are now a sourec of concern because they are potent greenhouse gases.
Chemical companies are developing new types of refrigerants that are ozone-safe and have low global warming potential, said researcher Brian Fricke of ORNL's Energy and Transportation Science Division. The question is how they will affect the energy efficiency of the equipment in which they're used. Brian, Omar Abdelaziz, and Vishal Sharma, also of ETSD, are conducting research to provide answers.
They are testing the energy performance of several proprietary next-generation refrigerants in actual supermarket refrigeration equipment using an instrumented two-chamber research setup, one representing the indoors and one the outdoors. Two 12 foot food refrigerator cases and three 12 foot freezer cases are in the indoor chamber, and their condenser and compressor rack are in the outdoor one. Plastic tubs filled with water simulate the load in the cases, and thermocouples measure the air temperature and the temperature in the tubs. “We’re measuring the effects on the various components that make up whole refrigeration systems,” Brian said.
Several industry partners are participating in the test, including chemical companies that are developing the new refrigerants and the equipment manufacturers who produce supermarket food cases.
“We’re evaluating these refrigerants in terms of energy performance in supermarket refrigeration systems and weighing that against the other environmental impacts,” Brian explained. To assess energy efficiency, they measure
refrigerant flow rates as well as temperatures and pressures throughout the system, including the food cases and the compressors and condenser.
“We’re using refrigeration equipment commonly used today. An owner doesn’t want to replace his equipment— he wants to drop in a new refrigerant into the equipment
he has,” he noted. The tests will provide data for the efficiency
of the different refrigerants and show equipment owners how using a particular refrigerant might affect their energy bills.
"Supermarket refrigeration systems take a large refrigerant charge, 2000 to 3000 pounds, and there is a high potential for leakage, so the potential environmental impact of leaks is significant," Brian said. On the other hand, reducing
the energy efficiency of the systems would cause them to use more power, which could lead to higher emissions of carbon dioxide, another greenhouse gas.
“Right now, there are no regulations in the US for the commonly used refrigerants with high global-warming potential,” Brian said. "Equipment manufacturers, chemical companies, equipment users, and regulators are all pushing for more environmentally friendly compounds.