EP2690377A1

EP2690377A1 - Cold beverage dispenser

Info

Publication number: EP2690377A1
Application number: EP20120177660
Authority: EP
Inventors: Stefano Tavolazzi
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 2012-07-24
Filing date: 2012-07-24
Publication date: 2014-01-29
Anticipated expiration: 2032-07-24
Also published as: PL2690377T3; EP2690377B1

Abstract

A cold water dispenser comprises a refrigerated tank connected to a water source and a refrigerating circuit comprising a compressor, a condenser and an evaporator in heat exchange relationship with said refrigerated tank. The refrigerating circuit comprises an auxiliary evaporator in heat exchange relationship with a portion of water circuit connected to the water source, a valve system being provided in the refrigerating circuit in order to feed the auxiliary evaporator when temperature of dispensed water is below a predetermined threshold.

Description

The present invention relates to a cold water dispenser comprising a refrigerated tank connected to a water source and a refrigerating circuit comprising a compressor, a condenser and an evaporator in heat exchange relationship with said refrigerated tank.
The above kind of cold water dispenser can be a standalone appliance or it can be associated to a refrigerator. With the term "tank" we mean any kind of reservoir, including several coils of pipe adjacent to or in contact with the evaporator.
Current solutions are based on the use of a tank system which, after a first batch of water (based on size of the tank) is dispensed, does not dispense water at the correct temperature (warmer than required).
It is an object of the present invention to provide a cold water dispenser of the above type which can provide an unlimited cold water supply for beverage dispensing systems.
According to the invention, the above object is reached thanks to the features listed in the appended claims.
According to the invention, an unlimited cold water supply is obtained through an auxiliary evaporator which acts as a booster cooling system without freezing the water when a large amount of water needs to be dispensed (for instance when a big jar has to be filled with cold water). During a normal dispensing (for instance of a glass of water), the traditional system (cold storage tank) is used.
According to a preferred feature of the invention, a temperature sensor placed on the water pipe at or adjacent the cold water dispenser triggers automatically the shift from the normal dispensing mode to the booster dispensing mode. According to a further feature of the present invention, the refrigerating circuit comprises electro valves placed upstream the first and second evaporator in order to divert the flow of refrigerant towards the first evaporator in the normal dispensing mode or to the second evaporator in the booster dispensing mode. According to a further embodiment of the present invention, the refrigerating circuit comprises a by-pass conduit which connects, through an electro-valve, the delivery of the compressor with the auxiliary evaporator and then to the suction side of the compressor. Such further feature provides a significant energy saving because no electrical heater is required in order to avoid freezing and because the "booster" system runs only when is needed.
Further features and advantages of the present invention will become clear from the following detailed description, with reference to the attached drawing which shows a schematic view of the refrigeration circuit and of the cold water dispensing system according to the invention.
With reference to the drawing, the cooling system according to the invention is provided with a refrigerating circuit RC and with a water circuit WC. The refrigerating circuit RC comprises a compressor K, a condenser Q and a first evaporator element EVAP 1 which is connected to the compressor K through an electro valve B upstream a capillary pipe H.
The water circuit WC comprises a water cooling system including a tank or reservoir device C1 which contains water fed by a three-way valve TW (position D) connected to a main water line tap R through a filter M, the device C1 being in heat exchange relationship with the evaporator element EVAP 1 of the refrigerating circuit RC. Such heat exchange relationship may be of any kind; for instance, the evaporator element EVAP 1 can be a pipe wound around a metallic tank, or it can be a coil placed inside the tank, or it can be a flat evaporator placed in an insulated cavity where a water tank or reservoir is placed.
The device C1 is provided with a temperature sensor X connected to a temperature control unit (not shown) which switches on and off the compressor K according to the temperature setting in order to dispense cold water at the required temperature.
Anytime customer starts to dispense cold water for instance in a glass Z, the valve TW in its position D on the cold water circuit opens and water from the line flows to the device C1 pushing cold water out to the dispensing nozzle and so to the glass Z.
This operation mode occurs typically during small amount of water dispensing, for instance when a glass of about 200ml has to be filled.
The outlet water dispensing is provided with a second temperature sensor Y connected to the temperature control unit which measures continuously the dispensed water outlet; when the customer keeps dispensing water (for instance when a jar has to be filled), the outlet temperature rises and if the value is higher than the setting value, the electronic control activates automatically an electro valve C and closes the valve B so that the refrigerant goes to a second or auxiliary evaporator EVAP 2 through a capillary pipe F. This evaporator is in heat exchange relationship with a device C2 which contains water fed by the three-valve TW (in its position E) connected to the main filtered water line tap R. The device C2 may be a serpentine-shaped pipe in contact with the second evaporator EVAP 2, as a double-pipe heat exchanger. Of course other type of heat exchangers can be used. The second evaporator element EVAP 2 is the booster system which cools down water quickly and provides a continuous large amount of still cold water.
When the continuous dispensing operation is completed, the three-way valve TW (position E) closes and stops the water flow outlet, while the electronic control unit opens the valve B and closes the valve C to run according to a "normal" setting, where only the small evaporator EVAP 1 is used to guarantee the correct water temperature to be ready for dispensing to the next user. Instead of the two valves B and C, a single three-way valve can be used as well.
At this time, i.e. after having dispensed a large amount of cold water thanks to the "booster" mode, the water remaining into the "booster" water circuit of the device C2 linked to the evaporator EVAP 2 can potentially start to freeze due to thermal inertia of the evaporator which remains at very low temperature for a long period of time.
In order to avoid this potential freezing, the temperature control checks the temperature of the water into the pipe of device C2 by a third temperature sensor W and while the compressor K is running on evaporator EVAP 1, opens an electro valve A to provide some hot gas to the second evaporator EVAP 2 to keep the water contained into the device C2 always at the right temperature and avoid freezing.
This operation lasts only few minutes, to allow avoiding freezing the pipes, and then the valve A closes and valve B opens so the refrigerant can flow again through the evaporator EVAP 1 (normal operation mode).
Additionally, to avoid potential compressor starting issue due the pressure difference between high pressure side and low pressure side of the refrigerant circuits, before the compressor switches on, the valve A opens and after the compressor is started, it automatically closes and the temperature control switches on the valve B to cool water in the water circuit C1.
A check valve G is provided on the suction line of evaporator EVAP 1 to avoid refrigerant back flow while evaporator EVAP 2 is running.
A simplified potential execution of the solution according to the invention is composed by the following parts:

compressor with a power of 50-80 Kcal/hr;
thin and wire condenser provided with fan; dimension about 200x200x3 cm
capillary pipe with a flow rate of about 7-8 l/m ( glass dispensing);
capillary pipe for booster evaporator with a flow rate of about 4-5 l/m;
first evaporator external diameter: 8 mm, length 2-3 m;
booster evaporator external diameter: 8mm ,lenght 10-12 mt.;

Condenser Q can be either thin and wire or static "reyert" type both provided with fan (not shown) controlled by the temperature control which adjusts the speed accordingly to the settings.
Water route outlet on the booster circuit C2 is in counter-current with respect to the refrigerant path flowing to the evaporator EVAP 2 to improve performances; reservoir pipes of the booster water circuit and evaporator pipe can be coaxial or side welded together and covered by glycol or the like to enhance heat exchange.
The solution according to the invention allows a continuous cold water dispensing and, at the same time, provides energy saving because it does not require a massive sealed system and big compressor capacity.

Claims

Cold water dispenser comprising a refrigerated tank (C1) connected to a water source (R) and a refrigerating circuit (RC) comprising a compressor (K), a condenser (Q) and an evaporator (EVAP 1) in heat exchange relationship with said refrigerated tank (C1), characterized in that the refrigerating circuit (RC) comprises an auxiliary evaporator (EVAP 2) in heat exchange relationship with a portion (C2) of water circuit (WC) connected to the water source (W), a valve system (B, C) being provided in the refrigerating circuit (RC) in order to feed the auxiliary evaporator (EVAP 2) when temperature of dispensed water is below a predetermined value.
Cold water dispenser according to claim 1, wherein the valve system comprises a first valve (B) upstream the evaporator (EVAP 1) and a second valve (C) upstream the auxiliary evaporator (EVAP 2), such first and second valves (B, C) being alternatively switched on and off.
Cold water dispenser according to claim 1 or 2, wherein downstream the water source (R) a three-way valve (TW) is placed and adapted to feed water to the refrigerated tank (C1) or to said portion (C1) of water circuit (WC).
Cold water dispenser according to any of the preceding claims, wherein the refrigerating circuit (RC) comprises an auxiliary valve (A) adapted to allow passage of hot refrigerant downstream the compressor (K) to the auxiliary evaporator (EVAP 2) in order to avoid water freezing in said portion (C1) of water circuit.
Cold water dispenser according to any of the preceding claims, wherein said portion (C1) of the water circuit (WC) and the auxiliary evaporator (EVAP 2) are in counter-current heat exchange relationship.
Cold water dispenser according to any of the preceding claims, wherein between evaporator (EVAP 1) and the auxiliary evaporator (EVAP 2) a check valve (G) is placed.
Cold water dispenser according to any of the preceding claims, wherein a first temperature sensor (X) is associated to the refrigerated tank (C1) for providing temperature signal to a control unit in order to drive the refrigerating circuit (RC) accordingly.
Cold water dispenser according to claim 7, wherein a second temperature sensor (Y) is placed at or in the proximity of water dispensing for providing a temperature signal to the control unit in order to drive the valve system (B, C, A) accordingly.
Cold water dispenser according to claim 4, wherein it comprises a third temperature sensor (W) in said portion (C2) of the water circuit (WC) in order to drive auxiliary valve (A).