CHAPTER VI REFRIGERATING SYSTEMS. History and Principles of Refrigerating Systems. — The following chapter is devoted to historical data and the general principles underlying the operation of the principal refrigerating systems. The air refrigerating machine works on a principle of cooling by the absorption of sensible heat, and was one of the first types given consideration. Absorption refrigerating machines were also given early consideration. The inherent advantages of the compression refrigerating machine, in which advantage is taken of the latent heat of evaporization, were early recognized and this type of system, consequently, was subjected to development and perfection at an early date. A chemical method for producing refrigerating effects has been used for centuries, but of course, the commercial application of such methods is limited, on account of the high cost of producing such refrigerating effects. Following a discussion of the refrigerating systems, attention is given to the requirements of a household system, in which special attention is devoted to the design and construction of the different component parts of such systems.
Gorrie Air Machine. — The first air refrigerating machine was invented by Doctor Gorrie at New Orleans about 1850. Air was compressed in a cylinder and delivered to a chamber which was immersed in the cooling water. The pressure in the chamber was maintained at about 15 pounds per square inch above the pressure of the atmosphere. Water injection was used to partly cool the air during compression. Both air and water were delivered to the receiver. The air in the receiver was further cooled by the water on the outside. Then the air was expanded in another cylinder discharging at about atmospheric pressure. The expanding air was mixed with a quantity of brine which was injected into the expansion cylinder. The expanding air cooled the brine to about 20* F. This cold brine was used for ice making or refrigeration.
<Callout type="important" title="Important">The Gorrie machine required careful water management and precise pressure control.</Callout>
Kirk Air Machine. — Dr. Alexander Kirk invented a closed cycle air machine about 1861. This machine used a confined mass of air, operating always at pressure considerably above atmospheric pressure. Machines of this same type were made by Allen, an American, and Windhausen, a German.
Open Cycle Air Machine. — The open cycle air machine consists of two cylinders called a compression cylinder and an expansion cylinder. Air from the room which is to be cooled is taken in the compression cylinder. It is compressed and therefore warmed. This compressed air is then cooled by circulating water. This air is then made very cold by expansion to atmospheric pressure. Upon reaching this condition it is returned to the cold room. Open cycle air machines of this type were proposed by Lord Kelvin and Professor Rankin about 1852. The first actual machine operating on this principle was made by Giffard in 1873. At a later date, machines of this type were made, namely the Bell-Coleman and other improved designs by Mr. Lightfoot, Messrs. Haslam and Hall.
<Callout type="risk" title="Risk">Open cycle air machines can be inefficient due to heat loss during compression.</Callout>
Allen Dense Air Machine. — The dense air machine is used to some extent on boat installations. In this system air is compressed to about 250 pounds and then cooled by the cooling water. This cooling is usually performed by a copper coil immersed in water. The air is then passed through a moisture separator, after which it is conducted to the expansion cylinder. In this cylinder the air is expanded to about 60 to 70 lbs. pressure and a very low temperature. The 70 lbs. air is then passed through an oil separator before being returned to the compressor to start another cycle. A primer pump is used to automatically supply make up air. Machines of this type require considerable attention to eliminate trouble from ice forming within the evaporator, due to freezing the water vapor supplied by the make up air. Lubrication is rather difficult on a machine of this type. This system of refrigeration has not proven successful for small household machines, although the use of air as a refrigerant has some important advantages in this particular field of refrigeration.
Low Pressure Air Refrigeration System. — A recent development in household refrigerating machines operates on the principle of accelerating the evaporization of ammonia or alcohol by blowing air through the liquid. The air is compressed by a blower to a pressure of 10 to 15 lbs. gauge. The blower is usually direct-connected to the motor and operates at motor speed. This process is claimed to operate at efficiencies better than those obtained in the usual compression system.
Water Vapor Absorption Machines. — In the absorption type machine, two substances are used which have an affinity for one another so that one unites or dissolves in the other when they are cold, but they separate readily when heated. Sulphuric acid when cold has a great affinity for water. Heating a sulphuric acid and water mixture drives off water vapor. This vapor is condensed by the cooling water. The acid is then cooled and reabsorbs the water vapor at a low temperature and a very low pressure. There is a very low vacuum during both parts of the cycle. The absorbing substance acts like a pump and maintains a low pressure during the cooling cycle. This principle was first used by Professor Leslie in 1810. A small machine of this type was made by M. E. Carre in 1875 for household work. It consisted of an air pump, and a chamber to contain the acid. A rod on the pump handle served to agitate the surface of the sulphuric acid.
<Callout type="tip" title="Tip">Absorption machines are less efficient but can be useful in certain environments where other refrigerants are not available.</Callout>
Ammonia Absorption Machines. — The ammonia absorption machine works on the principle of ammonia dissolving in water. One quart of water will dissolve about 500 quarts of ammonia gas. Ammonia has a higher vapor pressure than water and the absorbing is accomplished under a pressure considerably above atmospheric. Heating a water and liquid ammonia mixture drives off ammonia gas. This gas is condensed by the cooling water. The water is then cooled and reabsorbs the gas at a low temperature. In actual practice only part of the ammonia is driven off from the aqua solution. The ammonia absorption machine was invented by F. Carre about 1858-1860. The original machine was a very crude affair, consisting merely of two vessels — one surrounded by cold water, the other containing the ammonia and water. The original patent in the United States was issued October 2, 1860, the reissue being dated February 18, 1873. The Carre machine, subsequently improved by Mignon and Rouart in France, Vass and Littmann in Germany, Reece, Mort, Nicolle, and others in England and Australia, marked a great era in mechanical refrigeration.
<Callout type="warning" title="Warning">Ammonia is highly toxic and requires careful handling to avoid inhalation or skin contact.</Callout>
History of the Vapor Compression Machine. — The first machine of the vapor compression type was invented by Jacob Perkins, an American, and patented in England in August, 1834. It was further developed by Twining, who took out his English patent in 1850. This machine was not a commercial success. It was not until 1857 that James Harrison of Geelong, Australia, made a compression machine using sulphuric ether which was of commercial value. Messrs. Siebe and Gorman later manufactured these machines in England. This refrigerant is not used today.
<Callout type="important" title="Important">The vapor compression system became the dominant technology due to its efficiency and reliability.</Callout>
In April, 1867, Prof. P. H. Van der Weyde of Philadelphia, Pa., obtained patents for the use of naphtha, gasoline, petroleum, ether and condensed petroleum gas (chimogene) as refrigerants, and obtained patent on his compression refrigerating machine. Mr. D. L. Holden, after his successful experience in San Antonio with the Carre ammonia absorption machine in 1865, purchased the patent rights of Prof. Van der Weyde and built his first compression machine at the Novelty Iron Works in New York City. Several other compression refrigerating machines using ammonia were built and installed by Mr. Holden in New Orleans, La., Bonham, Houston and Galveston, Tex.; Mobile, Ala.; Thibodauxville, La.; Selma, Ala., and Charleston, S. C.
132 HOUSEHOLD REFRIGERATION In 1868, Charles Tellier, of Passy, near Paris, took out patents on his compression apparatus, whose refrigerating agent was methylic ether, and which was designed to make ice and to refrigerate air and liquids. The date of his letters patent in the United States was June 5, 1869, and one of his machines was erected in the Old Canal Brewery, New Orleans, by George Metz, with the object of producing cold, dry air, and making ale and lager beer without the use of ice. In the seventies appeared the inventions of Francis D. Coppet of New Orleans; Franz Windhausen, Germany; Prof. C. P. G. Linde of Munich, Bavaria; Raoul P. Pictet, Geneva, Switzerland; Thos. L. Rankin of Ohio; Martin & Beath, San Francisco; A. T. Ballentine of Maine; James Boyle of Texas, and David Boyle of Chicago.
132 HOUSEHOLD REFRIGERATION In 1877 Mr. Enright designed and built a machine having a vertical double-acting compressor, and in the fall of the year one of this type was installed in the brewery of A. Ziegele of Buffalo, N. Y. In 1878 patents were issued to the inventor, not only for his double-acting compressor, but for the pipe point commonly known as the Arctic. Vincent constructed a chloride of methyl compression machine in 1878. M. Raoul Pictet invented a sulphurous acid machine about 1875. This machine is used in France and Switzerland. Dr. Carl Linde, of Munich, introduced the ammonia machine in 1876. In 1878, the first compression machine made by C. J. Ball was erected at Dallas, Tex. Upon his retirement he was succeeded by his son, P. D. C. Ball, who conducted the business under the name of the Ice & Cold Machine Co., until 1920, at which time the name of the company was changed to the Ball Ice Machine Co.
The first De La Vergne refrigerating machine was placed in the Hermann Brewery, New York City, in 1879. One of the inventors of the original apparatus, John C. De La Vergne, was engaged in the brewing industry in 1876, and in 1881 he formed the De La Vergne Refrigerating Machine Co., for the manufacture of the so-called De La Vergne-Mixer Machine, the second patentee being William M. Mixer of New York.
The refrigerating department of the Frick Co. originated about 1881, when either Mr. Jariman or Mr. Ferguson of Baltimore, Md., submitted plans of machinery to George Frick, and plants were subsequently erected for several parties in that city. About 1882 Peter Weisel, the founder of the business now conducted by the Vilter Manufacturing Co., Milwaukee, Wis., designed a double-acting horizontal refrigerating machine which the firm of Weisel & Vilter commenced to build in that year. The first machine was installed in the Cream City Brewery, Milwaukee.
In 1885 W G. Lock, an engineer of Sidney, Australia, patented a compound compressor for ammonia consisting of two single-acting high and low-pressure pumps, side by side. Patents covering the idea were issued as early as 1867, and the Lock improvements, together with the St. Clair compound machine, manufactured by the York Manufacturing Co., were great improvements on the originals. Thomas Shipley, vice-president and general manager of the company, made a number of most important changes and improvements on the originals, and also patented other improvements on ice making and refrigerating plants.
The compression refrigerating machine is now produced by a number of the leading manufacturers in the United States. The carbonic acid machine was patented by Raydt in 1881 and later by Windhausen in 1886. This type machine is made by Messrs. J. and E. Hall of Dartford, Eng., The Linde Co., Messrs. Haslam and Hall and the Pulsometer Co.
Vapor Compression Machines. — Most of the mechanical refrigeration of today is performed by vapor compression machines. In this process, a liquid is used which can be alternately liquefied and vaporized. 132 HOUSEHOLD REFRIGERATION The liquids in common use are ammonia, sulphur dioxide, methyl chloride, ethyl chloride, ether, and carbon dioxide. The refrigerating cycle may be divided into four different phases : 1. Throttling effect through expansion valve. 2. Vaporization process in cooling coils. 3. Compression of vapor in compressor. 4. Cooling and condensing of vapor in condenser. Refrigeration is produced by the latent heat of vaporization of these substances, all of which have a relatively low boiling point. The vapor resulting from the vaporization of the liquid in the cooling element is conducted to the suction side of the compressor. This vapor usually reaches the compressor in a slightly superheated condition. The compressor then forces the gas into the condensing element, where it is liquefied by cooling, usually by means of water or air. The liquid refrigerant is then allowed to return to the cooling element through an expansion valve or a restricted orifice. This cycle is continuous.
The restricted orifice must always be sealed on the condensing or high pressure side with liquid refrigerant, in order to function properly. FIG. 9.— COMPRESSION REFRIGERATING SYSTEM. The cooling element may operate either on a flooded or dry system. In the flooded system, a relatively large amount of the liquid is stored in the cooling element and a regulation of the restricted orifice keeps this amount nearly constant. In the dry system, the regulation of this orifice is usually controlled by the pressure of the low or evaporating side.
Statistics show that more than 90 per cent of all the refrigerating and ice making plants in the United States today are operated on the ammonia compression system. This is only true of the commercial or larger size plants as the household systems favor sulphur dioxide compression machines. The compression refrigerating system is shown diagramatically by Fig. 9. The five essential parts shown are the compressor, condenser, receiver, expansion valve, and evaporator. An ordinary piston type of compressor is illustrated.
Chemical Methods. — It is a well known fact that when ice melts the temperature remains constantly at 32° F. Heat is supplied to cause this physical change of state from a solid to a liquid, and if the rate of heat supply be increased or decreased there will be no change in the temperature of the ice but simply a change in the rate of melting. Mixtures of some salts with ice and of certain salts with water or acids do not follow this same rule. For example, if salt is mixed with ice the rate of melting will tend to increase more rapidly than the heat is absorbed and the temperature will fall below that of melting ice. The temperature will be depressed a certain amount depending upon the per cent of salt used. United States Department of Agriculture Bulletin Nd. 98 gives the temperature resulting from mixtures of ice and salt as follows: Per Cent Salt Degrees F. 0 32 5 21 10 20 15 11 20 1.5 25 —10. The temperature of water may be lowered as much as 40° F. by dissolving ammonium nitrate in it. Ice may be formed in this way. The lowering of temperature by means of ice and salt mixtures is shown graphically in Fig. 10. This figure illustrates how the temperature is reduced as the percentage of salt is increased. This chart is for ordinary salt, sodium chloride.
Water for Cooling Food. — Farmers' Bulletin No. 375 of the United States Department of Agriculture gives the following, in reference to cooling of foods, by means of water: There are many ways of lowering temperature by utilizing the fact that water when evaporating draws off heat from surrounding objects. If a pitcher of water be wrapped with a cloth and placed in a room where the temperature is 80° F., the water will gradually cool until it reaches the same temperature as the air, but if the water be allowed to evaporate, the temperature of the water will fall below that of the air.
<Callout type="gear" title="Gear">Evaporative cooling systems can be useful in hot climates where electricity is not available.</Callout>
Key Takeaways
- Early air and absorption refrigeration methods were developed but faced limitations.
- The vapor compression system became dominant due to its efficiency and reliability.
- Ammonia was a key early refrigerant, though it poses significant safety risks.
Practical Tips
- Utilize ice and salt mixtures for cooling in emergency situations where electricity is unavailable.
- Consider using evaporative cooling systems in hot climates as an alternative to mechanical refrigeration.
- Understand the principles of vapor compression refrigeration to better maintain modern household appliances.
Warnings & Risks
- Be cautious with ammonia, as it can be highly toxic and requires careful handling.
- Avoid open cycle air machines due to their inefficiency and potential for heat loss during compression.
- Ensure proper water management in absorption systems to prevent freezing issues within the evaporator.
Modern Application
While early refrigeration techniques like ice and salt mixtures are still useful in emergency situations, modern vapor compression systems have vastly improved efficiency and reliability. Understanding these historical methods can provide valuable context for maintaining and troubleshooting contemporary appliances.
Frequently Asked Questions
Q: What was the first air refrigerating machine invented?
The first air refrigerating machine was invented by Dr. Gorrie in New Orleans around 1850. It used compressed air to cool water, which then cooled brine and produced cold brine for ice making or refrigeration.
Q: Why did the absorption refrigeration method become less popular compared to vapor compression systems?
Absorption refrigeration methods were less efficient and required careful management of substances like ammonia. They also faced safety concerns due to the use of toxic chemicals, making them less practical for widespread commercial and household use.
Q: What are some key components of a vapor compression refrigerating system?
A vapor compression refrigerating system includes a compressor, condenser, receiver, expansion valve, and evaporator. These components work together to cycle the refrigerant through its liquid and vapor states to produce cooling.
Q: How did early absorption machines use chemicals for refrigeration?
Early absorption machines used substances like sulphuric acid and water, where the acid had a strong affinity for water. By heating the mixture, water vapor was driven off, which could then be condensed to produce cooling.
Q: What is the significance of the Gorrie machine in refrigeration history?
The Gorrie machine was significant as one of the earliest air refrigerating machines and demonstrated the potential for using compressed air to cool water and produce cold brine. It laid groundwork for future developments in refrigeration technology.