UPDATED: Presentations of innovative CO₂ systems at the 2010 Herrick Conferences in Purdue

The School of Mechanical Engineering at Purdue University has a long tradition in organising conferences to present industry and researchers the opportunity to exchange ideas, information and cutting-edge research in the area of compressors and closely related fields.

The International Compressor Engineering Conference and the International Refrigeration and Air Conditioning Conference held in parallel every two years, typically focus in the former case on CO₂ compressors & expanders, compressor valve designs, lubrication issues in compressors as well as new compressor concepts as well as in the latter case i.a. on alternative refrigerants and working fluids, efficiency improvements, heat pumps, natural refrigerants, supermarket refrigeration systems and transcritical CO₂ systems.

In regards to current environmental concerns, a third conference has been added this year, the 1st International High Performance Buildings Conference, talking i.a. about air distribution systems, thermal systems and controls, heating and cooling plants, low-energy cooling, as well as natural and hybrid ventilation to give just a few examples.

The conferences were preceded on 10 and 11 July 2010 by short courses on the “Introduction to Compressors (Compressors 101)”, “Supermarket Refrigeration” and “High Performance Building Technologies”, giving the opportunity to students and participants to polish up their knowledge in the respective fields in preparation to the conference.

Experimental Performance of a Prototype Carbon Dioxide Compressor

One of the most interesting presentations, will be held on Thursday morning in the session dedicated to CO₂ compressors. Seth Holloway, W. Travis Horton and Eckhard A. Groll from Purdue University, as well as Dan Sherman and Marc Albertin from EcoThermics have worked together in assessing the performance of a CO₂ prototype compressor in comparison to predecessor prototypes and other compressors.

The test was carried out with a compressor of semi-hermetic, single-stage, axial configuration with an estimated cooling capacity of 10-14 kW, using a hot-gas bypass test apparatus. While operating at steady-state conditions, parameters such as suction pressure, suction temperature, discharge pressure, discharge temperature, refrigerant mass flow rate, and compressor power consumption were measured and recorded.

Software systems such as REFPROP and Engineering Equation Solver helped calculate the thermodynamic properties and performance measures from the experimental data, showing volumetric efficiencies ranging from 67-75%. Isentropic efficiencies ranged from 49-73% and overall isentropic efficiencies from 38-59%.

This demonstrates significant improvements in comparison to the predecessor prototype compressor as well as competitive performance marks in regards to other carbon dioxide compressors.

EcoThermics has a history of working with natural refrigerants in the HVACR sector and also held in conjunction with the conferences a press conference on 14 July, on the energy savings potential offered by the use of CO₂ as refrigerant while announcing the availability of the first compressor produced in the U.S., working with this natural refrigerant. The press conference took place at 10 am in the West Lafayette Hilton Garden.

The company announced at the event the first real-world application of the system for the processing and packaging of honey in a StollPak honey processing plant in Ohio. Honey needs to be heated and maintained at temperatures high enough so that it flows out of barrels and through pipes, avoiding crystallisation. The CO₂ heat pump also provides free cooling to the plant’s boiler room as an added benefit.