Compressors expanders using

Meruit Inc. has developed a novel air bearing for use in a small high-performance automotive fuel cell turbocompressor. A suitable air bearing must be inexpensive, durable, stable, and stiff enough to survive the automotive environment. Meruit has one main task to validate its air bearing for automotive compressor/expander use. Development of an air bearing turbocompressor meeting DOE s specifications was also pursued under the project. 

In addition to their automotive use, PAO oils also find appfication in industrial and aircraft hydraufic fluids, gear oils, compressors, and environmentally sensitive appfications. They are also used in multipurpose greases for army, navy, nuclear, and industrial appfications. Expanding use has led to a growth rate of PAO production from 1985 to 1990 of 19% per year (28). 

A fuel cell system for automobile application is shown in Figure 1.5 [41]. At the rated power, the PEMFC stack operates at 2.5 atm. and 80°C to yield an overall system efficiency of 50% (based on lower heating value of hydrogen). Compressed hydrogen and air are humidified to 90% relative humidity at the stack temperature using process water and heat from the stack coolant. A lower system pressure is at part load and is determined by the operating map of the compressor-expander module. Process water is recovered from spent air in an inertial separator just downstream of the stack in a condenser and a demister at the turbine exhaust. 

Dattorro, 1987] Dattorro, J. (1987). Using digital signal processor chips in a stereo audio time compressor/expander. Proc. 83rd AES Convention, New York. preprint 2500 (M-6). 

The achievement and utilization of low temperatures require the use of various specialized pieces of equipment including compressors, expanders, heat exchangers, pumps, transfer lines, and storage tanks. As a general rule,... 

The need to obtain greater recoveries of the C2, C3, and C/s in natural gas has resulted in the expanded use of low-temperature processing of these streams. The majority of the natural gas processing at low temperatures to recover light hydrocarbons is now accomplished using the turboexpander cycle. Feed gas is normally available from 1 to 10 MPa. The gas is first dehydrated to a dew point of 200 K and lower. After dehydration the feed is cooled with cold residue gas. Liquid produced at this point is separated before entering the expander and sent to the condensate stabilizer. The gas from the separator is expanded in a turboexpander where the exit stream can contain as much as 20 wt % liquid. This two-phase mixture is sent to the top section of the stabilizer which separates the two phases. The liquid is used as reflux in this unit while the cold gas exchanges heat with the fresh feed and is recompressed by the expander-driven compressor. Many variations to this cycle are possible and have been used in actual plants. 

Fabricate a TIVM compressor/expander protot5qie using seals, porting, and materials selected from the simplified feature tests and evaluations. 

Based on the experience of two previous generations of scroll-based compressor/expander modules developed with DOE, design and build a hybrid compressor/expander module using both turbomachinery and scroll compression. 

Although the second alternative is more efficient and looks promising, it will not be taken into account in this study, as it will influence the combustion process and might be more difficult to retrofit to existing facilities. The calculated equipment costs only consist of the membrane costs and compressors/expanders, but are multiplied with an installation factor. The capital and operational costs adjusted with the parameters used in this study are shown in Tables 2.15 and 2.16. 

Investigations of prototypes for automotive air conditioning and some other appUcations show that well-designed systems can actually perform at levels reached by other refrigerants. One method that would greatly enhance the efficiency of CO2 cycles is the use of an expander instead of an expansion valve. An expander produces work that can be fed back into the compressor or used otherwise. In... 

Mechanical Expanders Reciprocating expanders are very similar in concept and design to reciprocating compressors. Generally these units are used with inlet pressures of 4 to 20 MPa. These machines operate at speeds up to 500 rpm. The thermal efficiencies (actual enthalpy difference/maximum possible enthalpy difference) range from about 75 percent for small units to 85 percent for large machines. 

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