One way the HVACR industry is doing its part in the effort is the creation of more efficient heating and cooling equipment. Ways to do that were explored in a symposium held the day prior to the opening of the International Trade Fair for Refrigeration, Air Conditioning, and Ventilation (IKK). The seminar was organized by the Information Centre on Heat Pumps and Refrigeration (IZW), and more than 125 participants from throughout the world were in attendance.
Commercial Refrigeration
Denis Clodic, of Ecole des Mines de Paris, an education and research institution, explored energy issues related to commercial refrigeration. He noted the increasing interest in indirect refrigeration systems for supermarkets. Secondary-loop technology was most often used compared with the more traditional direct-expansion systems, he said. "The competition between direct and indirect systems has led to the lower installation price of indirect systems, by taking advantage of the lower refrigerant charge, and to the development of some new indirect systems with efficiencies at least comparable to the one of new and well-designed direct systems," he said. "Gains are due to higher efficiency of heat exchange in the air coil."Because most supermarkets in Europe are not 24-hour operations, Clodic saw potential in the use of night curtains.
"The development of efficient and easy-to-use automated night curtains leads up to 35 percent of energy savings for vertical display cases," he said.
Regarding motors, he added, "Improvement of energy efficiency of electrical motors represents between 5 and 20 percent, depending on the base line."
Clodic called upon the industry to come up with more efficient defrost methods.
"Significant improvements are necessary for both better control of product temperature and for better energy efficiency," he said.
Energy Consumption
Like North America, those dealing with HVACR equipment in Europe see the energy consumption aspects of such equipment. Taking a detailed look at ways to improve the situation regarding commercial refrigeration was Pierluigi Schiesaro, R&D director for Arneg of Italy, an equipment manufacturer.He suggested the industry explore what might happen if condensing temperatures are decreased beyond current norms.
"By using an electronic expansion valve, it is possible to avoid the minimum pressure drop needed for a standard thermostatic expansion valve," said Schiesaro.
"Consequently, it is possible to optimize the condensing pressure at the minimum level permitted by the external ambient conditions. Using EEV makes it possible to optimize at the best value for superheating of the evaporator, improving the cabinet performances."
He then turned to the idea of increasing the evaporating temperature. "The evaporating temperature in an open display cabinet is a function of the evaporator design and dimensions and of the inlet air temperature," said Schiesaro.
"The inlet air temperature is dependent on the heat exchange inside the cabinet and, above all, by the warm external air infiltrations that depend on the design and distribution of the air flow and from the strength of the air curtain inside the cabinet."
For reducing the warm external air infiltrations and increasing the evaporating temperature, it is necessary to improve the design of the cabinet, said Schiesaro, "so as to optimize the distribution and circulation of the air inside."
Compressor Technologies
Norbert Kammer, of Copeland SA Belgium, said energy savings can be realized with innovative compressor technologies.He said "intelligent system designs" can "provide cooling and refrigeration in a more-efficient manner." Such new technologies provide "more flexibility in providing the requested cooling capacity and realizing optimized refrigerant circuit designs."
Continuing research, said Kammer, will result in "air conditioning and refrigeration systems, as well as compressors, which will operate in the thermodynamically highest achievable level yet in an economically feasible manner."
Publication date: 12/05/2005
