Patent GB-992490-A (GB)
Title: Upright refrigerator showcase
IPC: A47F3/04
Filed: 1962-03-09
Abstract: 992,490. Refrigerating. F. G. LAMB. March 9, 1962, No. 9112/62. Heading F4H. An open-fronted refrigerated show-ease has a curtain of air which is dehumidified by cooling and then refrigerated during recirculation, and an additional outer protective curtain of cool air. As shown in Fig. 1, the show-case comprises three side-by-side units and has outer insulated side walls 2, 3 and inner thermally conductive walls 5. The show-case may be closed when not in use by a roller shutter 16, Fig. 2, concealed in a canopy 13 and extending downward to a lower bumper 12. Each unit includes two separate air circulatory systems A and B. In the inner system A, air is drawn through inlet 10, covered by a screen 11 and a filter (not shown), over one of two dehumidifying refrigerating coils 140, 144 and a main refrigerating coil 100 by four coaxial centrifugal blowers such as 105. The blowers recycle the major part of the air back through the coil 100, such air being directed by curved guides 123, 124, and direct a proportion of the cold air through discharge openings such as 130 into a duct 30 at the back of the storage space. This duct communicates with an upper passage leading to outlet 35 and also with hollow shelves 6 having downwardly-directed outlets 56, 66, 76, whereby a series of air curtains are formed leading back to the inlet 10. The air is dehumidified by causing frost to form on coils 140, 144, a flap valve 150 being time-controlled so as to enable the air to pass alternately over each of these coils while the other coil is being defrosted, e.g. by hot gas from the compressor (not shown) of the refrigerating system. The defrost water is led from lines 155 to a main drain line 156. In the outer system B, air is directed along four parallel paths around the outside of the casing insulation 23 by four coaxial blowers such as 190, thus forming a multiple outer air curtain between upper outlets 170, 172, 173 and 174 and corresponding inlets arranged below the inner inlet 10. This outer air system acts as additional insulation. An example is given of temperature gradients of the multiple air streams in which the temperatures range from + 60‹ F. for the outermost stream issuing from outlet 174 to - 10‹ F. for the inner streams issuing from the shelf outlets and outlet 35. Fluorescent lights 80 may be provided. In a modification, Fig. 6, some of the air from system A passes out through slots 380 beneath the shelves and the top passage, the size of the slots being adjusted by slides 385, and the proportion of air passing into each shelf is determined by pivoted flaps 370-372 adjustable by screws 374-376. The dehumidifying/defrosting control valve 150, Fig. 2, is replaced by a pair of dampers 330, 332, controlled by a timer TM through linkwork 335, 337. Normally the dampers are in an intermediate position, Fig. 12, enabling air to pass over both coils 301, 302, but when one of these coils is to be defrosted the dampers are moved to an upper or lower position, Fig. 6. Electric heater elements 312, 313 which may be timed or thermostatically controlled are mounted on the dampers to prevent ice forming thereon, and similar elements 316 and 323 are associated with drain troughs 321, 322 to prevent re-freezing of defrost water before it is drained away; this water may be discharged by a pump. The main refrigerating coil 100 may be similarly defrosted when necessary (though less frequently than the dehumidifying coils) by by-passing hot refrigerant gas therethrough, and a further electric heating element 315 is associated with the main coil drainage trough 320. In a further modification (Fig. 10, not shown), the blower for system A is positioned between the main refrigerating coil and the dehumidifying coils, and each shelf includes an air return duct running parallel with and above the air discharge duct. Reference is made to an automatic temperature and defrost control system including electric relays.