Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B21/00—Machines, plants or systems, using electric or magnetic effects
  • F25B21/02—Machines, plants or systems, using electric or magnetic effects using Peltier effect; using Nernst-Ettinghausen effect
• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47F—SPECIAL FURNITURE, FITTINGS, OR ACCESSORIES FOR SHOPS, STOREHOUSES, BARS, RESTAURANTS OR THE LIKE; PAYING COUNTERS
  • A47F3/00—Show cases or show cabinets
  • A47F3/04—Show cases or show cabinets air-conditioned, refrigerated
  • A47F3/0404—Cases or cabinets of the closed type
  • A47F3/0408—Cases or cabinets of the closed type with forced air circulation
  • A47F3/0413—Cases or cabinets of the counter type
• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47F—SPECIAL FURNITURE, FITTINGS, OR ACCESSORIES FOR SHOPS, STOREHOUSES, BARS, RESTAURANTS OR THE LIKE; PAYING COUNTERS
  • A47F3/00—Show cases or show cabinets
  • A47F3/04—Show cases or show cabinets air-conditioned, refrigerated
  • A47F3/0482—Details common to both closed and open types

Definitions

• the invention relates to a refrigerated display case, in particular for perishable foods, with an approximately horizontal cooling plate made of thermally conductive material, a cooling element which is in thermal contact with the cooling plate, a hood which covers the cooling plate, and a blower which controls the air underneath the hood circulates and which is arranged under the cooling plate in an air duct which ends open on opposite edges of the cooling plate.
• Refrigerated display cases are often used to display perishable food in sales rooms and usually consist of an approximately horizontal cooling plate made of good heat-conductive material, on which the products to be cooled rest and which is covered by a hood to avoid energy losses.
• a transparent material of the completely or largely closed hood enables the customer or user to have a clear view of the food on display.
• the cooling plate is in thermal contact with one or more cooling elements, which may be produced by a circulating cooling medium.
• evaporators are preferably used as cooling elements in which cold is generated by vaporization of halogenated hydrocarbons. With regard to the heat flow from the refrigerated goods to the cooling element, two different principles are common.
• the products can be supplied with cooled circulating air, which avoids stratification of the air and ensures a uniform temperature under the entire hood.
• the cooling element is preferably arranged in a channel below the cooling plate through which the air is circulated with a blower.
• the air duct ends open on opposite edges of the cooling plate, air entering and exiting taking place through openings which are arranged either in, next to or at the edge of the cooling plate.
• the air duct is provided with an insulation, for example a foam layer, on the ground side.
• cooling of products is more effective and less lossy due to the heat conduction than direct cooling to a cooling plate due to the heat conduction.
• cooling is preferably carried out both by thermal contact with the cooling plate and by means of cooled circulating air.
• Peltier elements have proven to be advantageous due to their simple structure, easy assembly and freedom from vibration.
• their operation does not require evaporator liquids, which are often extremely harmful to the environment, nor an associated piping system, which, particularly in the case of small display cases, results in an unwieldy construction.
• the cables must not be detachable.
• Peltier elements are uncommon in cooling vitamins. Their disadvantage is a plate-like structure, in which cooling and heat dissipation take place on opposite sides, i.e. the waste heat always arises on the back of the object to be cooled. As a result of this design, it is not possible with commercially available Peltier elements in the prior art to construct a cooling plate with a duct arranged underneath for circulating air cooling, since the heat would be dissipated into the air duct.
• the object of the invention is to develop an inexpensive and easy-to-use refrigerated display case with a simple structure, in which the cooling takes place both via circulating air and by thermal contact with a cooling plate.
• the cooling element is a Peltier element, the cold side of which is provided with one or more heat sinks, the Peltier element is arranged in a wall of the air duct, the cooling plate rests on the heat sinks and the blower the air through the heat sinks or between encourages them through.
• the central idea of the invention is the use of one or more Peltier elements for cooling.
• Peltier elements for cooling.
• it is customary, plate-shaped Peltier elements.
• the products are cooled both by thermal contact with the cooling plate and by circulating the air inside the hood through a channel that runs below the cooling plate.
• the simultaneous cooling of the cooling plate and the air in the channel by the or the same Peltier elements is made possible by arranging them in the wall of the air channel, preferably in the wall opposite the cooling plate. There is therefore no direct contact with the cooling plate. Rather, the heat flow between the cooling plate and the Peltier element is ensured by one or more heat sinks, preferably cooling fins, which pass through the air duct and are in thermal contact with both components. Furthermore, a particularly effective cooling of the circulated air is ensured in this way. poses, as the fan conveys them through the heat sink or between them.
• the material of the cooling plate for example metals such as stainless steel or aluminum, glass, plastics such as plexiglass or PVC or composite plates with different layers of these or other materials.
• the proposed refrigerated display case is particularly suitable for the display of perishable foods, for example meat or cream products in sales rooms.
• the showcase combines the advantages of cooling by means of circulating air and thermal contact with the cooling plate.
• the cooling with Peltier elements ensures a simple and compact structure. This creates a preferably portable unit, the weight of which is comparatively low due to the lack of a compressor and evaporator.
• the refrigerated display case is therefore particularly suitable for temporary installation in different locations or as a transport container for perishable goods under
• the cold side of the Peltier element is covered by a thermally conductive film on which the heat sinks are placed.
• a thermally conductive film on which the heat sinks are placed.
• the cooling plate expediently forms the upper wall of the air duct and can be lifted off it.
• the cooling plate lies loosely on the heat sinks, so that they can be removed and good thermal contact is ensured.
• a cross-flow fan the axis of rotation of which is oriented perpendicular to the conveying direction, is particularly suitable as a fan for air circulation.
• its drive can be easily arranged outside the air duct so that it does not form a heat source within the air flow.
• the roller of the cross-flow fan which is preferably made of plastic, is expediently detachably fastened in order to enable simple cleaning and easy replacement.
• the heat flow through a Peltier element is largely determined by the temperature of its warm side. Therefore, the cooling effectiveness can be significantly increased by good dissipation of the waste heat.
• an effective heat exchanger results in a significant increase in cooling performance with unchanged Peltier elements by operating them in the optimal range of their working characteristic.
• Liquid-air heat exchangers are suitable as heat exchangers, as are common, for example, in motor vehicle construction.
• a second fan is expediently used to extract air from the outside of the refrigerated display case promote by the heat exchanger to ensure effective heat dissipation and thus a good efficiency of the refrigerated display case.
• the bottom of the air duct is preferably provided with openings, the arrangement of which is available in depressions in the bottom near the Peltier elements. Energy losses due to air flows through the openings can be avoided by the openings being closed by a material with capillaries or interconnected pores.
• a wick made of fiber material is suitable. The condensed water is absorbed by the capillary effect in the pores or capillaries of the material and directed to the opposite end, where it evaporates or drips off.
• the arrangement of the free end of the capillary or porous material in the air flow, which is driven through the heat exchanger by means of the second fan, has proven to be particularly advantageous. Due to the comparatively warm outside air, a complete evaporation of the condensate is guaranteed.
• the cooling of the display case to sufficiently low temperatures for the storage of food requires the cooling of the Peltier element and the adjacent cooling elements to temperatures below the freezing point. As a result, their surface freezes over before, so that the heat exchange deteriorates. It is therefore necessary to occasionally raise the temperature to above freezing, so that the ice formed melts and flows off as water.
• the Peltier element thus preferably has a control device which cyclically varies its temperature between the working range below 0 ° and the defrosting range above 0 °.
• the temperature variation takes place automatically by means of an automatic, preferably electronic control.
• the control range is expediently a few degrees in the vicinity of the freezing point, it being conceivable to change the amplitude or frequency of the cycles in accordance with sensed parameters, for example temperature or air humidity under the hood.
• the current direction can be reversed through the Peltier elements, so that their hot and cold sides are interchanged.
• the display case acts as a heating display case with a heating plate, the maximum temperature being determined by the Peltier elements.
• a comparatively good degree of efficiency arises especially when using the above-described liquid circuit with a heat exchanger, since additional thermal energy is supplied to the Peltier elements.
• a device for Disinfection of the air under the cooling hood or in the air duct is advantageous in order to suppress nucleation.
• radiation with ultraviolet light can be used.
• the air inside the refrigerated display case is comparatively dry, so that there is a risk of sensitive foods or products drying out.
• FIG. 1 top view of a refrigerated display case with the hood and cooling plate removed
• FIG. 2 cross section through the refrigerated display case along the line II-II 'in FIG. 1.
• the basic structure of the refrigerated display case consists of a trough-shaped lower part (1) and a transparent hood (2), which has a flap (3) that can be pivoted about a hinge for loading the refrigerated goods.
• the hood (2) is placed sealingly on the edge (4) of the lower part (1), whereby an insulating tape (5), which consists for example of rubber, forms thermal insulation and sealing.
• the cooling plate (6) which is preferably made of stainless steel and is loosely inserted, is used to store the chilled goods.
• the components for cooling the display case are arranged below the cooling plate (6) in the lower part (1), with guide devices (7) guiding the circulated air. Peltier elements are used for cooling
• the Peltier elements (8) are provided with a heat exchanger (10) through which liquid flows, which is preferably embedded in a foam, such as polyurethane. The heat is removed from the heat exchanger (10) by means of hoses or lines (11) through which a pump (12) conveys a cooling liquid to the heat exchanger (13) and back.
• the waste heat on the warm side of the Peltier elements (8) is transferred to a liquid in the heat exchanger (10), which circulates the pump (12) through the heat exchanger (13).
• the latter is cooled by air from the surroundings of the showcase, which is drawn in by the fan (20) through the inlet opening (18) and released into the surroundings after flowing through the heat exchanger (13) through the outlet opening (19).
• a voltage source (not shown), for example an accumulator or a mains connection, is used for the electrical supply of the components. Furthermore, it is expedient to provide a humidification device for the circulated air and, if appropriate, a disinfection device.
• the result is a refrigerated display case that is characterized by effective cooling with a simple and compact structure, easy to handle and easy to transport.

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• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)
• Cold Air Circulating Systems And Constructional Details In Refrigerators (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=7817106

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (13)

Family Cites Families (5)

• 1997
  • 1997-01-10 DE DE19700621A patent/DE19700621A1/de not_active Withdrawn
  • 1997-12-11 WO PCT/DE1997/002877 patent/WO1998030134A1/fr not_active Ceased
  • 1997-12-11 DE DE59704044T patent/DE59704044D1/de not_active Expired - Fee Related
  • 1997-12-11 EP EP97949984A patent/EP1014836B1/fr not_active Expired - Lifetime
  • 1997-12-11 AT AT97949984T patent/ATE202907T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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