Within the last five years the mechanical refrigerator has become a popular piece of household equipment. Its year-round use has caused architects and others interested in planning for the convenience of the housewife to recommend placing the new cabinet in kitchens and other convenient places, with little thought about the effect on the operation of the refrigerator. The purpose of this publication is to point out some of the conditions under which the refrigerator has been expected to operate successfully, and some of the effects of these conditions upon the operation of the machine

Brunig, M. P.

Lewis, E. B.

English

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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Historical Circulars of the Nebraska Agricultural Experiment Station Extension 5-1933 Fitting the Mechanical Refrigerator into the Home E. B. Lewis M. P. Brunig Follow this and additional works at: https://digitalcommons.unl.edu/hcnaes  Part of the Bioresource and Agricultural Engineering Commons, and the Mechanical Engineering Commons This Article is brought to you for free and open access by the Extension at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Historical Circulars of the Nebraska Agricultural Experiment Station by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. L 'I, Circular 45 May, 1933 Fitting the Mechanical Refrigerator into the Home E. B. LEWIS AN D M. P. BRUNIG Department of Agric ul tural E ngineering Exa mple s of crowd ed refridgeratorsTH E UNI VE RSIT Y OF NE BRAS KA COLLEGE OF AGR ICULTURE EXPERIMEN T STATION LINCO LN W . W . BU RR , Director I SU MMAR Y 1. The operating characteristics of the mechanical refrigerator are often disregarded when refrigerators are placed in alcoves. 2. Thir ty-five to fifty per cent incre ased operat ing costs may beincurred by faulty enclosures. 3. Wh ere the compressor unit is on top of the cabinet, the alcove ceiling should be 12 inch es or more above the coils. 4. Where the compressor unit is enclosed within the cabinet and receives ventilation either through the back or sides of the cabinet, a three-inch space mu st be provided at the back or side s in addition to the top space. 5. Where curtains, grilles, or other objects prevent sufficient circu la-tion of air over the top, a specia l air shaft may be in sta lled. Fitting the Mechanical Refrigerator into the Home E. B. LEWIS AND M. P . BRUNIGWithin the last five years the mechanica l refrigerator has become a popular piece of hous ehold equipment. Its year-round use has caused architects and others interested in plan-ning for the convenience of the housewife to recommend placing the new cabinet in kitchen s and other convenient place s, with little thought about the effect on th e operation of the refr igerator. The purpose of this publication is to point out some of the conditions under which the refrigerator has been expected t o operate successfu lly, and some of the effects of these condition s upon the operation of the machine. The effects on operation were studied in homes and in the laborator y, where duplications of propo sed settings were re-produced. 1 Service calls on refrig erator s were often found to have been necessary becaus e the cabinet had been placed in special alcoves, pantrie s with low ceilings, crowded corners, z > ...J A MODER N KIT CHEN DINING ROO M FIG. 1.-Some plans place the refrigerator to save steps. Th e mechanical refr ig-erator in such position may be too nearly enclosed . (D esigned by R. M. Lo per.) or other place s so built that ventilation or cooling of the com-pr essor and condens er coils was hind er ed. Picture s such as thos e on the front cover and plans similar to Figure 1 have appeared in mag azines and advert ising matter. Often there was no warn ing or sugg estion as t o possible effects on the operation of the refr igerator . 1 Many of the experimental placements were constructed by F. D. Yung in pre-par ing a thesis for an advanced de gree in Agricultural E ngineering at the Univer-sity of Nebraska. This work was done under the supervision of the authors. 4 NEBRASKA EXPERIMENT STATION CIRCULAR 45 In an ordinary ice box th e heat taken from the storage space is carried away by the water from the melting ice. In most mechanical refrigerator cabinets, heat is absorbed from the storage space when the liquid refrigerant expands into a gas as a resu lt of a change in pressure. When the gas has absorbed some of the heat, it is drawn into the compressor and condenser coils where it is liquefied and the heat dissi-pated . The liquid is then returned to the expansion equip-ment. This proces s is repeated over and over and thus re-moves heat from the storage space to produce the low tem-perature desired. For this reason heat can not be removed from a st orag e space in greater quantity or with greater rapidity than it can be driven from the condenser coils. If there is any lack of circu lation of air or if the air is too warm over the coils, condensation is not complete and the mixture of gas and liquid returning to the expa nsion chamber in the cabinet is warm and does not have capacity for absorbing sufficient heat. The result is poor refrigeration and too much operation of the compressor and motor 1 and the latter may become ex-cessively warm and stop. In the meantime cooling has been delayed in the food compartment. There are three common methods for installation of the condenser-coil unit: (1) on top of the cabinet; (2) within the cabinet, either above or below the food compartment; and ( 3) in a basement ( remote installation) . Sufficient air circulation about the coils in any installat ion is necessary for good operation. Each installation presents a littl e differ-ent problem. Lack of air circulation where the coils are placed on top of the cab inet is usually caused by a shelf too close to the top of the coils, curtains or grilles in front of the coils, or something placed on the coils. These conditions are illustrated on the cover . Retarded circulation when the coils are within a cabinet is usually caused by placing the refrig-erator close to a wall or other object so that air which must be drawn in and forced out the back or sides is baffled. When overhead cupboards. or shelves ar e too close to the top of the cabinet, the air coming up from the back or sid es is held back, also. Thus the warm air is slow in getting away and the compressor and coils are not given a chance to funct ion properly. (See Figure s 2B and 2C.) When the compressor unit is installed in the basement, the ref rigerator box may be enclosed as much as desired; in fact, closer confine-ment of the box usually means better efficiency becau se of better insulat ion. Even with remote installation, the con-denser unit must be exposed for free circulation of air. • I FITTING MECHANICAL REFRIGERATOR INTO THE HOME 5 I I I I I I I I I FOODSPACE L 1 FOOD1 : SPACE I I I I I I I : I ...J COMPRESSOR SPACE I I I I I I ' FOOD I SPACE I I I I I I I I I I I I I I A B C FIG. 2.-The type of cabinet in A would probably cease Lo function in an hour or two on a hot day if the she lf were low and a curtain or grille cut off a ir circulation. The cabinets in B and C would probably give trouble on a hot day if lo:!ded and pushed back ag11inst the wall, unless other provision were made for the escape of warm air from the coils. Trouble may be caused by covering this unit with a low table or other article which retards the escape of heat. · Observa tions both in the home and the laboratory show that the cost of operation may be increased at lea st 50 per cent when a cabinet is moved from an open position to a posi-tion in a crowded recess, and incr eased more than thirty-five per cent by changing the shape or size of the recess. These increases are often produced without causing mechanical trouble. Much greater increases may be incurr ed tem-porarily , but the causes would soon bring mechanical diffi-culties with the motor, compressor, or any of the thermal protective devices. Experiment s have shown that where heating radiators are enclosed by screens and grilles in front and shelves over the top, some spacing is necessary at the back and top. Too great interference of convect ion currents and poor heating result unle ss these spacings are definite for each type of radiator or enclosure. Similar ly, if the refrigerator cabinet Allen, John R., and Walker , J. H.: Heating and Ventilation , 2nd edition. 6 NEBRASKA EXPERIMENT STATION CIRCULAR 45 is one having the condensor on top as in Figure 2A, and the monitor of coils is cooled by natural cooling, any shelf low over the top or any curtain or grille dropped in front causes the small convection currents to circle about with very littl e velocity to force the warm air away. Rai sing the shelf at least 8 inches above the top of the monitor or providing an upright air shaft would allow this warm air to escape and be replaced by air cool enough to take heat from the coils . Placing the sides and back of this type of cabinet aga inst the inside cool walls of the home does not hinder the opera-tion. The walls may furnish sufficient protection to make the cost of operation lower than that of the same cabin et in an open-room position, provided the warm air is given a chance to get away from the coils. If the cabinet has the condenser, compressor, and motor installed within the cabinet as pictured in Figur es 2B and 2C, the heated air must pass out the back or sides and up and away, as indicated by the small arrows. It was found by trial tests that the cost of operation is greatly increased when the space at the sides or back, where louver s or other open space was provided for air transmission, is decreased to less than three inches. Some manufacturers have made little pro-jections to prevent placing their cabinet so close to walls that the warm air can not escape r eadily. The warm air has a chance to rise when space is provided, but provision must sti ll be made for this warm air to escape over the top of the FIG. 3.-A partial view of instruments and refrigerator cabinets u sed for the tests. FITTING MECHANICAL REFRIGERATOR INTO THE HOM E 7 cabinet as illu strated or up through some air duct to the roof or a cool upp er room space . Figure 3 shows part of the set-up for the laboratory test runs . Room temp eratur es wer e controlled automatically, with electric heating units for rai sing the temperature, and water radiators and ice for lower ing the temperature. In each case fans were used to give quick adjustments and to hold temperature gradients with in a narrow range. Recording thermometers and precision mercury thermometers recorded all temperatures; a graph ic watt-meter and a watt-hour meter showed energy consumpt ion. Controls on the cabinets wer e checked and set for definite storage space tempe ratur es for open-r oom tests . Any variat ions from these tempera-tures during the runs while cabinet s were enclosed are in-dicated by the solid lin es shown in Figures 4, 5, and 6. The average temp eratures here wer e very littl e different from the check-run temp erature s and were gover ned enti rely by the automatic contro ls in st alled as regular equipment in the cabinets. 0 0 .J 2 30 l I I I I I ENERG Y CONSUMPTION REFRIGERATOR NO.I I TO P PACINGZERO INCHES SIDE SPACING I I HEAVY LOAD J I INCH REAR SPACING10.l:1.,,, ,,,, ENERGY co· 24 12 6 4 2 0 TOP SPACING INC HES FIG. 4.-Changing the space over the top of the cabinet changed con-sump t ion of electricity as much as 25 per cent . Room temperature was maintained at 80 ° F. in these tests, while many kitchens in Nebraska have summer temperatures exceeding 90 °. 8 NEBRASKA EXPERIMENT STATION CIRCULAR 45 Figures 4, 5, and 6, made from a sma11 part of the test data, give some indication of the effect any change in air circula-tion space may have on the cost of operation of typical cab-inets. In obtaining the data from which the curves were made, cabinets were first operated in a constant-temperature room as near 80° F. as possible. Temperature regulation is indicated in Figures 5 and 6. Each machine was given a definite load for a 48-hour opera-tion in the open-room position . The machine was then enclosed in an alcove or recess made of insulating material and operated for the same length of time with the room tem-perature and the refrigerator load the same as during the open-room operation. On each of the two charts the dotted lines indicate the average controlled temperature in the room, the temperature in the refrigerator, and the amount of energy needed for the open-room check runs. The solid lines indicate the room and refrigerator temperatures and increased energy consumption caused by a change in the size or shape of the enclosure about the refrigerator in the test runs. The curve in Figure 4 indicates that energy consumption of a mechanical refrigerator, having the compressor unit en-closed in the cabinet, increases greatly when the ceiling of an alcove is less than 12 inches above the top of the cabinet. This is true with either the one- or four-inch space at the rear of the cabinet. The cabinet used when the data for this curve were obtained had a slight projecting edge that held the enclosure out from the cabinet ½ inch. The refrigerator used when data for the curves in Figure 5 were obtained had the monitor of coils on top of the cabinet. Extra insulation at the sides and back, when sufficient over-head space was provided, aparently lowered the energy con-sumption. This condition was probably due to improved air circulation and in some cases may be a definite reason for placing a refrigerator in an enclosure. The dotted lines indicate "check runs" from open-room test-run data. Figure 6 shows that the energy consumption is increased very rapidly when the spacing at the rear of the cabinet used for obtaining these data was three inches or less. The immediate increase shown in energy consumption ( solid curve compared to dotted line) was caused by the top of the en-closure resting on the cabinet. Figures 4, 5, and 6 show data from the tests. Their in-terpretation, as well as the interpretation of other data obtained, has led to the conclusion that any cabinet having a compressor coil unit on top must have at least 12 inches FITTING MECHANICAL REFRIGERATOR INTO THE HOM E 9 a: I I NO, 2 -ZERO I NCHES ZERO INCHES { 0 / _ __ _ C ENC OSED ;--' z T ENCLOSED -1 REfRI NET OPEN 30 18 6 3 0 T OP S PACING I NCH ES -----FIG. 5.-- Most of t h e data for energy consu mp tion were obta ined wh en t he roo m t emp er at u res were not excessive ly hig h or t he tempera-tu re in th e cabinet very low. Wh en freezing temperat ures insi de and high te mper atu res ou ts id e we r e u sed, t he energy-consu mpt ion increase was much greater for each enclosure having a lower shelf. 10 NEBRASKA EXPERIMENT STATION CIRCULAR 45 ENERGY CONSUMPTION VS. REAR SPAC NG I I I ZERO INCHES TOP ZERO INCHES SI DE a.. J I I-ENERGY CON V CABINET 0 4 CABINET ....,_ TEMPERATURE-CA NET IN OPEN ROOM--REFRIGERATOR TEMPERATURE ET ENCLOSED ---REAR SPACING - I NCH ES FIG. 6.-When the only air available t o the compressor -coil unit mu st come from the rear, the use of electrical energy increa ses very fast when the cabinet is pushed against the wa1l. Similar in-creases would be shown if a wall at the side shut off air from a side ventilate d unit . .. I FITT ING MECHANICAL REFRIGERATOR INTO THE HOME 11 of clearance over the top of the coils for circu lat ion. If any grilles or curtains are placed in front of the coils, some air shaft similar to that indicated in Figure 2B should be pro-vided . If the compressor is contained within the cab inet, there must be a clearance of at least three inches at the rear if the compr essor unit gets ventilation from t here, or at the sides if openin gs for air are at the sides. This must be in add ition to the clearance on top or to an air shaft leading upward from the sides or rear. Forced circulation reduces the clearance needed. If prop ,er air circu lating and ven t ilat-ing conditions are not prov ided, the user of the electrica l or mechanical refr igerator cabinet can expect greater energy consumption than is necessary. [5M] 

Fitting the Mechanical Refrigerator into the Home

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Fitting the Mechanical Refrigerator into the Home

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