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1983 Technical Papers
5th Annual Meeting
The Development of the Hallscrew Compressor for Ammonia Refrigeration
Author: G. W. Ashmole
It is apparent that the single screw compressor has interesting geometric features which enable it to combine the advantages of a positive displacement machine with many of the advantages of a balanced rotary machine with respect to low bearing loads. An evaluation of the single screw compressor is not complete without looking at the possibilities for development beyond the immediate horizons. Other geometries are available within the single screw concept which potentially allow small sizes of compressor and high pressure ratios to be achieved with improved performance. These geometries involve the use of conical main rotors and cylindrical gate rotors and have already been produced in the air compressor field. The possibilities for the reduction of oil with the consequent elimination of much of the ancillary equipment currently required by screw compressors is a major aspect of ongoing single screw development. The fundamental geometry and the materials of construction of the Hallscrew are both conducive to the achievement of these goals in the near future. This would then permit the screw compressor to be applied throughout the refrigeration industry with no more complication than that traditionally expected with reciprocating machines.
Piping is Piping…Or Is It?
Author: William V. Richards
With the present popularity of flooded and liquid over-feed systems in freezing plants, there exists many potential operating cost penalties due to pressure drop in overfeed risers. A new method for sizing over-feed risers to minimize pressure loss is described in this paper. Some calculated losses are shown for several different riser designs. Also two alternative methods for eliminating riser losses are reported along with field results using liquid return systems and primary coolant systems.
Life-Cycle Cost of a Cold Storage Door Repair or Replace
Author: George C. Balbach and Thomas D. Pease
The cold storage door is a unique piece of equipment. It is an integral part of any facility, and the only moving part of the structure. The door is essential to the material handling system and plays a major role in determining productivity, the prevention of energy loss and profitability. Not surprisingly, the door requires a lot of attention. It must be maintained, repaired and kept clean. This is why we will repeatedly stress great care in door selection to assure minimum maintenance and maximum reliability. Every product, however, has an Economic Life, defined as that period of time after which it should be discarded or replaced because of reduced profitability. This paper will examine a door which may be near the end of its Economic Life and suggest a process for determining available alternatives and making an effective decision.
Industrial Refrigeration: Let's Do It Right
Author: Richard H. Stamm, P.E.
The industrial refrigeration industry is in much better shape now than it was in the 1960's partially due to the efforts of IIAR. The U.S. needs more effective refrigeration and air conditioning systems. The industrial technology affords systems that can be 100% more effective than most commercial air conditioning systems. The IIAR should take on broader goals, agressive goals, instead of just defensive, and provide the standards, qualifications, and education that is necessary to expand our horizons. There is also a major problem of system responsibility. With an agressive position by the industrial refrigeration industry, and the IIAR, there is no reason the industry couldn't once more be a rapidly growing, profitable, industry, and provide for a real need for the country. The saleman's creed is "Find a Need and Fill It!". The need is there, the industrial refrigeration industry has the technology, production, and contracting capabilities to fill it. There is no real reason this organization couldn't double it's growth every year for the next ten years. All you have to do is get off your back sides, screw up your courage and business sense and do it!
Operating an Energy Efficient Refrigeration System: A Case Study at Ranco Freezer Storage
Author: George R . Souleret
This paper looks at a case history in perspective with other jobs CII has done and will pinpoint areas where the most savings will occur. Note that the general design of the refrigeration system does not change, only the operation of it.
Device for Oil Separation and Heat Exchanging for Vapor Compression Refrigeration Systems
Author: Henry B . Bonar, II
Patent abstract: A method and apparatus for removing oil from the refrigerant in a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator, and a vertical oil separation and heat exchange column into which hot compressed refrigerant vapors containing entrained oil are introduced to flow upwardly counter currently with cool refrigerant liquid introduced to flow downwardly in direct intimate mutual contact, said column comprising (1) an inlet vapor distributor to disperse vapors throughout the cross section of the column to flow upwardly around baffles and to be removed in the top of the column and be directed to said condenser, (2) an inlet liquid line comprising an hydraulic leg wherein the liquid is of sufficient pressure to resist the pressure of said vapors, (3) a means for distributing said liquid throughout the cross section of said column to fall by gravity to a pool of liquid in the bottom of the column, (4) an outlet from said pool of liquid directed to said evaporator and (5) an outlet for removing oil separated from said refrigerant liquid.
What Every Ammonia Engineer Should Know About Freon
Author: Michael J. Zion, P.E.
This paper covers aspects of the Ammonia/Freon industry from the perspective of a mechanical specialty contractor who does a lot of business in refrigeration. It covers the affects of laws passed in New Jersey on the use of ammonia, a brief history of the development of Freon, early freon system designs and applications, specifics about a dairy with a 30,000 lb R-22 system, difficulties with oil return in freon systems, and compares ammonia and freon equipment ratings.
Ammonia and Air-Conditioning
Author: Lance J. Domke P.E. and Jack Carney
This paper describes a concept which combines features from both commercial air conditioning and industrial refrigeration. Discussed herein are the advantages of air-conditioning systems with thermal storage and comparison of ice and water as thermal storage media. Defined procedures are offered for cooling load profile analysis, selection of major equipment and design conditions, and distribution system design.
Potential for Energy Conservation in Freezing
Author: Leo D. Pedersen, Ph. D.
Currently NFPA is involved in an energy efficiency study of freezing operations in cooperation with National Marine Fisheries Service. The monthly variation in fuel consumption over the year and a variation from year to year is shown; but the figure doesn't show very much about how energy efficient the plant is operating. The evaluation of energy consumption has to be tied together with production, and it is obvious that the energy consumption is closely tied to the production level. Further, the curve indicates that the energy cost factor is composed of a fixed cost and a variable cost component. A relatively small amount is production dependent. The same relationship can be found by evaluating the boilers.
Development of a Variable Volume Ratio Screw Compressor
Author: J. W. Pillis
The double helical rotary screw compressor has been successfully applied in the refrigeration industry since the mid to late 1950‘s. Characterized by high volumetric and adiabatic efficiencies, stepless capacity control, ability to operate over a wide range of compression ratios, pulsation free operation, and good reliability, the screw compressor has gained a significant position in the refrigeration market. However, one factor that has limited the field of application of the screw compressor has been its “fixed volume ratio”. The introduction of the “movable slide stop” has eliminated this restriction by allowing the compressor’s volume ratio to be adjusted during operation. This innovation allows significantly improved efficiency over wide ranges of application. In order to explain how the moveable slide stop works, the basics of screw compressors will be briefly reviewed.
Small Screw Compressors for Industrial Applications
Author: A. Lundberg
The paper describes a newly developed screw compressor series in the capacity range 40 to 200 TR on ammonia. The compressors feature oil injection and stepless capacity control like the larger screw compressors. The rotors are geared to give optimized tip speed for the different compressor sizes and a highly standardized size range. The compressor unit includes a compressor vertically mounted on an open type flange motor. Oil filter and suction strainer are integrated in the compressor housing. Water or refrigerant cooled oil coolers are normally used.
A Study of Performance of Solar Cooling Plant
Author: Gur Saran Das
The performance of a 10 ton cold storage has been investigated using aqua-ammonia in the vapour absorption refrigeration system operated by solar energy. The effect of the following variables has been studied and it has been found that the system performance is greatly affected by them : (a) the generator temperature, which is related to both the collector and refrigeration system design : (b) the ambient temperature, which governs the condenser and absorber temperatures of the refrigeration system : (c) the temperature to which the ammonia water vapours are cooled in the dephlegmator in order to obtain purer ammonia travelling to the condenser, and (d) the number of glass covers of the collector which greatly affects the useful heat gain in the collector. The effects of various parameters are reported in the form of graphs showing the variation in the performance of the system as functions of these parameters.
Advancements in Screw Compressor Oil Cooling Systems
Author: Paul Szymaszek
Depending on the size of the unit and the operating conditions, the oil cooling load can range from 5 to 30% of the total heat rejection to the refrigeration condenser. Because of the large quantities of heat, it is of the utmost importance that this heat be dissipated in an efficient manner. Over the years, several different methods have been used to remove the heat absorbed by the oil. These systems include water/glycol to oil shell and tube heat exchangers, liquid refrigerant to oil shell and tube heat exchangers, and liquid injection systems. Initially, screw compressor units employed water cooled oil cooling using a water to oil heat exchanger. The most serious disadvantages of these system is the resultant fouling and corrosion of the water side heat transfer surface and the relatively high initial equipment cost. Today, with the increasing scarcity of water, its corrosive properties, and fouling characteristics, water cooled oil cooling has largely given way to oil cooling systems utilizing system refrigerant.
Looking at the Ammonia Refrigeration Facility from an Insurance Company View
Author: R. B. Nielsen
It should come as no great surprise that the operator of ammonia refrigeration equipment and the insurer of the same have one common goal - continued operation of that equipment. The operator/owner looks for uninterrupted service to gain the maximum use of the system thereby allowing the best return on his investment. In this process, he gains the continued good will of his customers and/or clients. Obviously, an insurer wants the equipment to run faithfully since it increases his chance for a profit. Under these circumstances, insurance is often looked upon as a necessary evil - something you hope you will never have to use but nice to have if and when a fortuitous event that results in loss, takes place. I'm also confident that we insurers are sometimes looked upon as a nuisance with all of our recommendations and conditions for either coverage to attach or continue. For these reasons I'd like to spend some time putting you in the shoes of an underwriter to give you some insight into their analysis of conditions and exposures. In the process, I will try to explain how these things relate to the premium charged.
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