Ray W. Herrick Laboratories, Purdue University

The Herrick Laboratories were established in the 1950s with a grant from Ray W. Herrick for graduate student education and research. More than 500 master's and doctoral theses have been written by our graduate students, along with numerous articles in technical journals and reports to sponsors. Typically, 50-60 graduate students work at the Laboratories at any given time. Research projects range from applied to fundamental, merging education with the research needs of industry and government. Principal investigators are drawn primarily from the School of Mechanical Engineering at Purdue University. Contact with industry is maintained through an Industrial Advisory Committee and the many short courses and conferences aimed at industry hosted by the Laboratories each year. Engineering research conducted at the Laboratories is largely sponsored by industry with additional support from government agencies.

Projects range from short-term applied research to long-term fundamental research. The engineering disciplines of thermodynamics, fluid mechanics, heat and mass transfer, acoustics, combustion, dynamics and vibrations, signal processing, mechanics, and stress analysis form the basis of these studies. A blend of system or component modeling, experimentation, identification, and computer simulation is used to gain insight into the behavior of mechanical and thermal systems.

Thermal Systems Research

From its beginning in the late 1950's to the present day, research in the areas of thermodynamics, heat transfer and fluid mechanics (thermal systems) has been an integral part of the Herrick Laboratories. Primarily this research has been in cooperation with the heating, ventilating, air-conditioning and refrigerating (HVAC&R) industries. Since 1958, over 300 students (approximately one-third at the doctoral level) have earned advanced degrees through their research in HVAC&R. Early work in the areas of heat transfer and thermophysical properties was geared towards improving the efficiency of equipment. Over time, equipment research evolved to include issues of product cost, reliability, comfort, noise and vibration. With the advent of high speed digital computers, the focus of much of the work changed to mathematical modeling and simulation, including computer-aided design (CAD) and computerized design optimization procedures. The development of computer simulation tools not only improved the capabilities for equipment design and analysis, but has also provided practical methods for designing and analyzing complete systems.

During the energy shortages of the 1970s, energy utilization became a focus of the research programs. Illumination, heating and cooling of space, water heating and refrigeration in residential, commercial, and industrial buildings use about one-third of all the energy consumed in the U.S. Although traditional energy-related research has primary encompassed design and control of equipment and systems, energy consumption can also be reduced through improved maintenance and servicing. Research in this area includes the development of computer automated techniques for condition monitoring, fault detection, and diagnostics. Reducing electric utility power demand through the use of new systems (e.g., thermal storage) and controls is also an important research area.

In recent years concerns with the ozone depletion and global warming problems have become additional focal points of the HVAC&R research programs. Approximately one-third of the chlorofluorocarbons (CFCs) consumed in the U.S. is used in refrigeration and air-conditioning. CFCs are considered a major factor in ozone depletion and global warming problems. The changeover from CFCs to alternative refrigerants impacts equipment design and may also have a significant impact on energy use.

Current research areas include:

· modeling of buildings, HVAC&R equipment, and systems
· intelligent control of systems with thermal storage
· diagnostics for vapor compression cooling equipment
· performance of alternative refrigerants/refrigerant mixtures in, and alternative technologies for, HVAC&R equipment and systems
· reliability, performance, modeling, and noise control of positive displacement compressors
· modeling of two-phase flow in refrigerant systems

In order to address both industry and societal concerns within the area of HVAC&R, fundamental engineering approaches to design and control of equipment and systems are needed. HVAC&R research is aimed at removing the scientific barriers to good designs, good control, development of suitable standards, and the utilization of proper materials. The HVAC&R area is an interdisciplinary research effort which includes a wide variety of projects in disciplines such as acoustics, vibrations, controls, mechanics, design, materials, thermodynamics, heat transfer, fluid mechanics, and computer science. The common goal is fundamental and applied research that will assist the HVAC&R community in the continuing evolution of improved heating and cooling equipment and systems. Research activity in the HVAC&R area is closely allied to the concerns of industry and with the programs of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the Air-Conditioning and Refrigeration Institute (ARI), the Association of Home Appliance Manufacturers (AHAM), the International Institute of Refrigeration (IIR) and the International Institute of Ammonia Refrigeration (IIAR). Most of this research is conducted at the Ray W. Herrick Laboratories, a graduate student research facility of the School of Mechanical Engineering.

All research projects have a strong educational component, and virtually all lead to theses for either a Master of Science or PhD degree. Most research funding for the programs is provided by industry, reflecting an unusually close link with companies and industry associations.

Thermal Systems Facilities

Experimental facilities, instrumentation, and equipment for data acquisition, reduction, computation, and display are available for HVAC&R research. Two large environment chambers can simulate indoor and outdoor conditions and are used to study the performance of heating and cooling equipment and for simulation experiments in the development of intelligent building controls and automated equipment diagnostics. A fully instrumented air coil test facility is available to measure the performance of air-to-refrigerant or air-to-secondary fluid heat exchangers both with and without dehumidification. Test stands for air-conditioners, heat pumps and reversing valves, expansion devices, and water heaters and compressors are among the specialized equipment available for these research programs at the Herrick Laboratories. Emerging areas of research are the newer positive displacement compressors including scroll and screw compressors.

A large portion of the Herrick Laboratories is dedicated to investigating the performance, efficiency, noise, and vibration of large HVAC&R equipment with cooling capacities of up to 100 tons. A large test setup was recently constructed for testing diagnostic methods applied to a 90-ton centrifugal chiller. In addition, a fully operational ice storage system is setup in this part of the laboratory. The system can be used to evaluate the performance of alternative control methods or cooling coils under a variety of time-varying conditions. The Herrick Laboratories also contain special purpose computers for the control of experiments and for data acquisition and reduction. These computers are also on the University network, facilitating remote access to data.

Thermal Systems Area Faculty

The faculty members at the Herrick Laboratories are associated with the School of Mechanical Engineering. Although a number of faculty are involved in interdisciplinary research, the following members form the core of the thermal systems area:

James E. Braun: Thermal systems modeling, analysis, design optimization, control optimization, and diagnostics with applications to space conditioning and refrigeration systems.

Raymond Cohen (Herrick Prof. of Eng.):Noise and vibration control, and mathematical modeling of various compressors.

Victor W. Goldschmidt Fluid: mechanics, thermo-systems, and energy utilization in HVAC&R equipment and systems.

Eckhard A. Groll: Performance optimization of CFC and HCFC replacements, natural refrigerants, refrigerant mixtures, alternative refrigeration cycles, and design optimization of cycle components.

Satish Ramadhyani: Numerical methods in heat transfer and fluid mechanics, cooling of electronic equipment, and refrigeration equipment and systems.

Werner Soedel: Vibrations and dynamics of elastic systems, including gases and fluids, stress analysis, acoustics, simulation of machinery dynamics, and fluid machinery, incl. compressors.

David R. Tree: Applied aspects of thermodynamics, fluid mechanics, and heat transfer to thermal systems (e.g., performance of HVAC&R equipment, internal combustion engines, and buildings), and fundamental nature of heat transfer in heat exchanger.

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