FR2491320A1 - Dishwashing machine with forced hot air drying - uses external contra-flow heat exchanger to transfer exhaust air to incoming air which is drawn in by fan and then heated - Google Patents

Abstract

The dishwashing machine draws in external air, heats it and directs it over the dishes in the dishwasher to dry them. The saturated air passes through a condenser to reduce its moisture content before it is exhausted to external atmosphere. The incoming air and the condenser are arranged as a contra-flow heat exchanger. The air is drawn in by an axial entry fan and directed up a pipe which is coaxial with the moist air outlet. The air pipe then turns downward and the air is admitted at the base of the dishwasher, passing over a heater as it enters. The warm air rises through the dish racks and exits from the top of the dishwasher to pass down the condenser pipe, giving up heat to the incoming air. The moisture falls down the condenser walls and is collected for disposal.

Description

Dishwasher fitted with a fan supplying fresh air
The present invention relates to a dishwasher provided with a fan which discharges fresh air which is injected through a heating device into the tank of the machine for drying the dishes, directed, in the moisture-laden state, through a condensing device and released into the ambient air.

 In a dishwasher of this kind known from American patent No. 30 26 628, cold fresh air supplied by the fan is mixed with the humid air as it enters the condensing device in order to prevent the outlet vapor from the latter into the ambient air. However, we observe at the same time this drawback that the air mixture of the condensation device therefore has a lower dew point than that of the hot air charged with humidity leaving the tank, so that the effect of the condensing device is reduced.

 The subject of the invention is a dishwasher, of the advertised type, in which the efficiency of the condensation device is improved.

 This dishwasher is characterized by the fact that the condensation device is established as a heat exchanger through which cold fresh air flows against the flow of moisture-laden air. We draw this advantage from it, because of the cooling of the condensation device with cold air and the separation between this cold air and the air charged with humidity, said humidity of the latter already condenses to a dew point. relatively high. In addition, the cooling of the condensing device has the effect of dehumidifying the highly charged air very strongly, so that when it is released into the ambient air, no water vapor is produced either. .

 In a preferred embodiment of the invention, the cold fresh air is conveyed by a tube coming from the fan and passing coaxially through the condensation device, established in tubular form.

 According to another possible advantageous particular feature of the invention, the cold fresh air tube opens, on the side of its outlet, into the stream of fresh air discharged by the fan. It is thus possible to reduce the energy consumed to heat the fresh air discharged into the tank, since the partial current of air passing through said tube undergoes heating in the latter.

 The invention will be better understood with the aid of the detailed description of an embodiment taken as a nonlimiting example and illustrated diagrammatically by the single figure of the appended drawing.

The dishwasher 1 has a tank 2 in the form of a box in which several baskets 3, 4 are placed to receive the dishes. A fan 5 also ensures the delivery of fresh air which is injected into the tank 2 of the machine from the bottom side through a heating device 6 to dry the washed dishes. The hot air evaporates the remaining liquid still adhering to the dishes and reaches the moisture-laden state in a condensing device 7 connected from above to the tank 2o
The condensing device 7 is arranged as a heat exchanger and comprises an external humid air tube 8 and an internal cold air tube 9 coaxial. The humid air tube 8 ends in an outlet tube 10 to which is assigned a container 11 for the condensate. The cold air tube 9, however, leaves the fan 5 and opens freely into the ambient air.

 The air saturated with humidity entering the tank 2 of the machine in the condensing device 7 undergoes in the humid air tube 8 a cooling, so that the water vapor which it contains condenses and s' flows into the container 11 through the outlet tube 10. The dehumidified air also escapes to the ambient air through the outlet tube 10. To evacuate the heat transferred to the device 7 during the condensation of moisture, and maintain a high efficiency of the device, a partial stream of cold fresh air discharged by the fan 5 is directed through the cold air tube 9 against the flow relative to the air charged with humidity. The fresh air thus heated leads to the ambient air.

 To reduce, unlike what happens in the aforementioned embodiment, the energy consumed to dry the dishes, we can, as shown in phantom in the figure, direct, from the count of its output, the tube of cold air 9 to the fan and inject the heated fresh air into the stream of fresh air discharged by the fan 9 upstream of the heating device 6.

Claims (3)

 1. Armpit washing machine with a fan that discharges fresh air which is injected through a heating device into the tank of the machine to dry the dishes, conveyed, in the moisture-laden state, to through a condensing device and discharged into the ambient air, dishwasher, characterized in that the condensing device (7) forms a heat exchanger through which cold fresh air flows against the air charged with humidity.  2. Dishwasher according to claim t characterized in that the cold fresh air flows through a tube (9) from the fan (5) and coaxially passes through the condensation device (7, 8) established in tubular form.  3. Dishwasher according to claim 2 characterized in that the cold fresh air tube (9) opens, on the side of its outlet, into the stream of fresh air discharged by the fan (5.