About The ACRC

Center Mission and Rationale
The Air Conditioning and Refrigeration Center (ACRC) has two major goals: to contribute technology toward the development of energy-efficient equipment that operates in an environmentally friendly way; and to provide a forum for industry to coordinate research and share results at the precompetitve stage.

The Center was founded in 1988 with a grant from the estate of Richard W. Kritzer, the son of the founder of Peerless of America, Inc.; a grant from the Illinois Governor's Science Advisory Council for laboratory facilities, and support from the National Science Foundation of the United States. The ACRC now operates with the support of approximately 30 industrial partners who provide funding for the "core" research program, and with grants and contracts from a range of government and private sector sponsors for additional projects.

Research Program
More than a dozen faculty members are involved in ACRC's research program. The systems under study include a wide range of thermal management and energy conversion systems. Related topics include, but are not limited to:

  • Properties. Viscosities, vapor pressures, and densities of refrigerant-lubricant mixtures and refrigerant blends.
  • Processes. Heat transfer and pressure drop, frosting, controls, tribology, and oil circulation.
  • Components. Evaporators, condensers, capillary tubes, orifice tubes, ejectors, suction-line heat exchangers, insulation, and flexible refrigerant tubing.

The ACRC research program involves about 40 graduate students and more than 20 undergraduates. Many students are attracted by the opportunity to participate in industrially relevant research. Many of the Center's students, upon graduation, are hired by ACRC's industrial sponsors, some are hired by other industry employers, some go to national laboratories, and some go on to academic careers.

Special Center Activities
The Center communicates detailed research results to its industrial sponsors in the ACRC Technical Reports series, and through monthly email reports to participating engineers. A typical research project yields one to three significan ACRC technical reports, plus occasional technical memoranda and other reports to sponsors.

The ACRC's modern equipment and facilities include:

  • Thermophysical property test chamber. Accurately controls temperature from 100°F to 400°F and pressure up to 35 atmospheres to obtain thermodynamic and transport property data for refrigerant blends and lubricant mixtures.
  • Condensation and evaporation loops. Measures local heat transfer and pressure drop coefficients in test sections of 1m, 3m, and 6m length. Refrigerant-lubricant mixtures and refrigerant blends are tested with smooth-and enhanced-surface tubes and microchannel extrusions.
  • Falling-film wind tunnel. Provides a realistic environment with vapor flow over falling-film evaporator or condenser tubes to determine falling-film mode transitions and local and averaged heat transfer behavior.
  • Evaporator and condenser wind tunnels. Support heat-transfer and pressure-drop studies over the range of air velocities and temperatures encountered in refrigerators and stationary or mobile air-conditioning applications.
  • Air-side wind tunnel. Provides a carefully controlled air flow for analysis of air-side enhancements. Naphthalene sublimation techniques are used to investigate effects on local heat transfer and surface efficiency.
  • Orifice and capillary tube facilities. Specialized test loops support investigations of suction-line heat exchangers and expansion device performance.
  • Environmental chambers. Capable of subjecting air conditioners and refrigerators to temperature and humidity conditions far outside the range of standard rating conditions.
  • Mobile and stationary air conditioning test facilities. Dedicated breadboard systems support studies of transient performance and system control strategies.

Some of the Center's accomplishments include:

  • Developing a device for online measurement of oil concentration in air conditioning and refrigeraion systems. A digital counter-timer together with an ultrasonic transducer determines oil concentration (within ± 0.25%) from the acoustic velocity in the refrigerant-lubricant mixture.
  • Making the first measurements of liquid refrigerant carryover at the exit of an evaporator, using a laser-doppler particle analyzer to measure droplet velocity and size distributions, and estaclishing their relationship to slug flow in the evaporator.
  • Designing and building a pressurized tribotester that provides a realistic test environment for evaluating friction and wear characteristics of compressor contact geometries, material pairs, and refrigerant-lubricant combinations. Found that tests run in a pressurized environment yield resulrs significantly different from those obtained under the nonpressurized conditions used by industry for screening studies in the past.
  • Obtaining detailed understanding of refrigerator cabinet heat transfer: investigating conductive, convective, and radiative phenomena in the door seal area; and determining sensible and latent loading during door-opnening transients.