WO2006074572A1

WO2006074572A1 - Hot and cold water dispenser and method of controlling same

Info

Publication number: WO2006074572A1
Application number: PCT/CN2005/000035
Authority: WO
Inventors: Guoxin Yu; Yuuichi Yakumaru; Tetsuya Saito
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2005-01-12
Filing date: 2005-01-12
Publication date: 2006-07-20
Anticipated expiration: 2007-07-12
Also published as: CN1969153A

Abstract

A hot and cold water dispenser includes a compressor (1), a radiator (2), a pressure-reducing mechanism (3), and an evaporator (4) all connected in series to define a refrigerating cycle, in which a refrigerant that operates in a supercritical state is filled. The radiator (2) is accommodated in a hot water tank (5), while the evaporator (4) is accommodated in a cold water tank (6).

Description

DESCRIPTION

Hot and Cold Water Dispenser and Method of Controlling Same

Technical Field

^• The present invention relates to a hot and cold water^' dispenser for supplying hot water and/or cold water and, in particular, to a s_.mall-sized hot and cold water dispenser capable ¹Of supplying hot water of a high temperature. The present invention relates also to a- method of controlling such a hot and cold water dispenser.

Background Art^'

Nowadays, not only a . small-sized hot - or cold water dispenser for

.supplying potable hot or cold water, but also a hot and cold water dispenser that is a combination of a hot water dispenser and a cold water dispenser is popularized. In the hot and cojd water dispenser, cold water is made by cooling tap water or the like'with an evapoηator in a refrigerating cycle, while hot water is made by heating such water with an electric heater provided independently of the refrigerating cycle. A hot and cold water dispenser capable of making both hot

^■ water and cold wafer has been recently proposed in which a vapor compression refrigerating cycle is utilized in, order to reduce electrical power consumption (see, for example, Chinese Utility Model Publication ZL01235617.4).

This conventional- hot and cold water dispenser makes use of R134a or R600a as a refrigerant in the refrigerating cycle and is provided with a hot water tank accommodating a condenser and a cold water tank aocommodating an evaporator. When the refrigerating cycle is in operation, water in the hot water tank is heated with the condenser, while water in the cold^'.water tank is cooled with the evaporator. If hot water of a high temperature is desired, an auxiliary heater is accommodated in the hot water tank. The use of heat of condensation of the i refrigerating^' cycle in making the hot water enhances the thermal efficiency and reduces the electrical power consumption, _.compared^' with the use of only the electric heater.

However, in order to obtain hot water of a high temperature, the use of R134a or R600a as the refrigerant in the refrigerating cycle increases the condensing pressure of the refrigerant, making it difficult to realize it due to an increase in compression ratio.. For this reason, hot water is first made at a certain condensing pressure causing no increase in compression ratio and is subsequently heated with the auxiliary heater, resulting in a reduction in the effect of electrical power consumption.

^' Further, because the R134a refrigerant is not a natural chemical substance, it is relatively costly and exerts a harmful influence on the environment. On the other hand, the R600a refrigerant is a natural chemical substance, but it is high in inflammability and has a possibility of explosion when leaking into the i ^• atmosphere. Accordingly, the use of this refrigerant entails any possible safety precautions, resulting in a high cost..

The present invention has been developed to overcome the above-described disadvantages.

It is accordingly an objective of the present invention to provide a hot and cold water dispenser^' capable of supplying both cold water and hot water of a high temperature by making use of a refrigerating cycle in which a relatively inexpensive and safe refrigerant that is gentle with the environment is used. Disclosure of the Invention

In accomplishing _, the above and other objectives, the . hot and cold water dispenser according to the present invention includes a . compressor, a radiator, a pressure-reducing mechanism, and an evaporator all connected in series to define a refrigerating cycle, in which a refrigerant that operates in a supercritical state is filled. The hot and cold water dispenser also includes ^■ a hot water dispenser for supplying hot water that is heated by the radiator and a cold water dispenser for supplying cold water that is cooled by the evaporator.

By this construction, both cold water and hot water of a high temperature can be obtained by operating the refrigerating cycle, and the electrical power consumption can be reduced.

It is preferred that carbon dioxide be used as the refrigerant, making it possible to reduce the load to the environment and to obtain hot water of a higher temperature.

The hot water dispenser may include a hot water ,tank having the radiator accommodated therein, while the cold water dispenser may include a cold water tank having the evaporator accommodated therein. In this case, because the hot and cold water dispenser can be used as both a cold water reservoir and a hot water reservoir, the utility thereof is enhanced.

If a feed water tank for supplying water to the hot water tank and the cold water tank is provided, water other than tap water can be used.

The present invention can provide a hot and cold water dispenser capable of supplying cold water and hot water of a high temperature by making use of a refrigerating cycle in which a refrigerant that is inexpensive, safe, and gentle with the environment is used. • Brief Description of the Drawings

The above^' and other objectives, and features of the present invention will become more apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings, throughout which like parts are designated by like reference numerals, and wherein: Fig. 1 is a refrigerating cycle of a hot and cold water dispenser according a first embodiment of the present invention;

Fig. 2 is a Mollier diagram schematically showing the operation of the refrigerating cycle of the hot and cold water dispenser of Fig. 1 ; ^■ _. Fig. 3 is a refrigerating cycle of a hot and cold water dispenser according a second embodiment of the present invention; ^'

Fig. 4 is a flowchart showing a control method for the hot and cold water dispenser of Fig. 3; Fig. 5 is a refrigerating cycle of a modification of the hot and cold water dispenser of Fig. 3;

Fig. 6 is a flowchart showing a- control method for the hot and cold water dispenser of Fig. 5;

Fig. 7 is a refrigerating cycle of a hot and cold water dispenser according a third, embodiment of the present invention;

Fig. 8A is a flowchart showing a hot water control method for the hot and cold water dispenser of Fig. 7;

Fig. 8B is a flowchart showing a cold water control method for the hot and cold water dispenser of Fig. 7; Fig. 9 is a refrigerating cycle of a modification of the hot and cold water

• dispenser of Fig. 7;

Fig. 1 OA is a flowchart showing a hot water^'control method for the hot and cold water dispenser of Fig. 9;

: Fig. 10B is a flowchart showing a cold water control rhethod for the- hot and cold water dispenser of Fig. 9;

Fig. 11 is a refrigerating cycle of another modification of the hot and cold water dispenser of Fig. 7; and

Fig. 12 is a flowchart showing a control method for the hot and cold water dispenser of Fig. 11. Detailed Description of the Preferred Embodiments Embodiment 1.

Fig. 1 depicts a refrigerating cycle of a hot and cold water dispenser according to a first embodiment of the present invention. As shown therein, the. refrigerating cycle is . constituted by a compressor 1 , a radiator 2, a pressure-reducing mechanism- 3, and an evaporator 4, all connected in series by piping. The refrigerating cycle is filled with carbon dioxide (CO₂) as a refrigerant. An expansion valve or a capillary tube is preferably used for the pressure-reducing mechanism 3. The radiator 2 is accommodated in a hot water tank 5, while the evaporator 4 is accommodated in a cold water tank 6.

The hot water tank 5 has a feed water line 7 connected thereto, and the cold water tank 6 similarly has a feed water line 8 connected thereto. Both the feed water lines 7, 8 are connected to a water service piping 9 and have respective valves 12, 13 attached thereto! The hot water tank 5 also has a hot water tap 10 for supplying hot water therethrough, and the cold water tank 6 similarly has a cold water tap 11 for supplying cold water therethrough.

Fig. 2 depicts a Mollier diagram (pressure-enthalpy diagram) schematically showing the operation of the refrigerating cycle of the hot and cold water dispenser according to the first embodiment of the present invention. ^■ Because carbon dioxide is used as the refrigerant in this embodiment, the evaporator 4 operates in a zone of wet vapor under a saturated liquid line 20 and a saturated vapor line 21 , while the radiator 2 operates in a supercritical state over a critical point 22. The operation of the hot and cold water ^' dispenser of the above-described construction is discussed hereinafter with reference to Figs. 1 and 2.

A gaseous high-temperature refrigerant compressed by the compressor 1 is introduced into the radiator 2 accommodated in the hot water tank 5 to heat water in the hot water tank 5. The refrigerant is then reduced in pressure to

^■ turn into wet vapor by .the pressure-reducing mechanism 3, and is subsequently introduced into the evaporator 4 accommodated ^'in the cold water tank 6 to cool water in the cold water tank.6, before it returns to the compressor 1. The use of carbon dioxide as the refrigerant can render the pressure in the evaporator 4 to be about 3 to 4 MPa and the pressure in the radiator 2 to be about 10 to 12 MPa. Accordingly, the compression ratio is not too high, making it possible to operate the compressor 1 without spoiling the reliability thereof. Also, because the radiator 2 operates in the supercritical state, the temperature of the refrigerant at the inlet of the .radiator 2 is high of being about 100⁰C. For this reason, the temperature of the hot water in. the hot water tank 5 can be readily increased up to about 8O⁰C to 90⁰C, enabling high-temperature water supply.

As shown in Fig. 1 , each of the hot water tap 10, the cold water tap 11 , and the valves 12, 13 is comprised of a solenoid valve, and each of the hot water

< S tank 5 and the cold water tank .6 accommodates a known level detector (not shown) such as, for example, a float switch for detecting water level in the tank 5, 6 and for outputting the detected water level. The solenoid valves and the level detectors together with the compressor ^■ 1 ^■ and the pressure-reducing mechanism 3 are all electrically connected to a controller 14, which outputs electric signals to control them.

A hot water supply button and a cold water supply button both mounted on the body of the hot and cold water dispenser are also connected to the controller 14 to selectively open or close the hot water tap 10 and the cold water tap 11 , respectively. Furthermore, the valves 12, 13 can be operated depending on the water level in the hot water tank 5 and that in the cold water tank 6, respectively, so that tap water may be automatically supplied to the hot water tank 5 and the cold water tank 6 from the water service piping ,9. Also, the operation of the refrigerating cycle can be interlocked with the action of the valves 12, 13 for automatic heating or cooling operation of the hot and cold water dispenser.

Although Fig. 1 depicts the case where water is supplied to the hot water tank 5 and the cold water tank 6 from the water service piping 9, a separate feed water tank may be provided to supply water to the hot water tank 5 and the cold water tank 6. • Ih this case, commercially available water other than tap water can be used, making it possible to. supply potable hot and cold water most suitable for health. Embodiment 2. Fig. 3 depicts a refrigerating cycle of a hot and cold water dispenser ^ι according to a second embodiment of the present invention, and Fig. 4 depicts a flowchart showing. a method of controlling the same.

The construction shown in Fig. 3 is the same as that shown in Fig. 1 in the refrigerant to be used in the refrigerating cycle and the like, but differs therefrom in the following points.

A feed water tank 30 is connected to both the feed water lines 7, 8 constituting first and second water supply lines, respectively. The hot water tank 5 is provided with a hot water temperature detector 33 such as, for example, a thermistor accommodated therein for detecting the temperature of the hot water in the hot water tank 5. The hot water tank 5 and the feed water tank 30 are mutually connected via a hot water circulating line 31 constituting a third water supply line, which returns the hot water in the hot water tank 5 to the feed water tank 30. A hot water circulating pump 32 is installed on the hot water circulating line 31. The hot water tank 5 accommodates a known level detector 37 such as, for example, a float switch for detecting water level in the tank 5 and for outputting the detected water level. The hot water circulating pump 32, the hot water temperature detector 33, and the level detector 37 are all electrically connected to the controller 14.

The operation of the hot and cold water dispenser of Fig. 3 is explained hereinafter with reference to the flowchart of Fig. 4. As described hereinabove, because carbon dioxide is used as the refrigerant, high-temperature heating is possible. For this reason, water in the hot water tank 5 can be heated up to the boiling temperature thereof' (100⁰C at the atmospheric, pressure) and, hence, it is necessary to prevent destruction of the hot water tank 5 due to expansion thereof or hot water supply at an excessively high temperature. For this purpose, the hot water temperature detector 33 is provided in the hot water tank 5 to control the feed water operation of the hot and cold water dispenser depending on the hot water temperature detected by the hot water temperature detector 33.

As shown in Fig..4, the controller 14 determines at step S 1 whether the hot water temperature Th in the hot water tank 5 is greater than an upper limit temperature (for example, 9O⁰C), and if the former is greater than the latter, the valve 12 is opened at step S2 so that the first feed water control for feeding water of a low temperature in the feed water tank 30 is conducted. At step S3, a determination is made whether the temperature Th detected by the hot water temperature detector 33 is less than a set temperature (for example, 80⁰C) lower than the upper limit temperature. If the determination at step S3 is YES, the valve

' 12 is closed at step S4 to stop water feed from the feed water tank 30, and the ' procedure proceeds to step S5.

Furthermore, if the hot water temperature Th in^' the hot water tank 5 is less than or equal to the upper limit temperature at step S1 , or if the hot water temperature Th is greater than or equal to the set temperature at step S3, the ^' procedure also proceeds to step S5. At step S5, a determination is made whether the water level Hh in the hot water tank 5 detected by the level detector 37 is higher than an upper limit level. if the water level Hh is higher than the upper limit level, the hot water circulating pump 32 is operated at step S6 so that the second feed water control for returning hot water in the hot water tank 5 to the feed water tank 30 is conducted, thereby preventing an overflow from the hot water tank 5 that may be caused by water feed from the feed water tank 30 to the hot water tank 5.

At step S7, a determination is made whether the water level Hh in the hot water tank 5 is lower than a set level that is lower than the upper limit level, and if the former is lower than the latter, the operation of the hot water circulating pump 32 is stopped at step S8, and the procedure returns to step S1.

Furthermore, if a determination has been made at step_* S5 that the water level Hh in the hot water¹ tank 5 is lower than or equal to the upper limit level, or if a determination has been made at step S7 that the water level Hh in the hot water tank 5 is higher than or equal to the set level, the procedure also returns to step Sl

The temperature 'control for the hot water tank 5 referred to above is particularly effective in the case where the operation of the refrigerating cycle is needed to make cold water in the cold water tank 6, i.e., the operation of . the compressor 1 is controlled depending on- the cold water temperature.

Fig. 5 depicts a modification of the hot and cold water dispenser of Fig. 3, wherein. the cold water tank 6 is provided with a cold water temperature detector ^'34 such as, for example, a thermistor accommodated therein for detecting the temperature of the cold water in the cold water tank 6, the cold water tank 6 and the feed water tank 30 are mutually connected via a cold water circulating line 35 constituting the third water supply line, which returns the cold water in the cold water tank 6 to the feed water tank 30, and a cold water circulating pump 36 is installed on the cold water circulating line 35. The cold water tank 6 accommodates a known level detector 38 such as, for example, a float switch for detecting water level in the tank 6 and for outputting the detected water level. The cold water circulating pump 36, the cold water temperature detector 34, and the level detector 38 are all electrically connected to the controller 14.

Fig. 6 depicts a flowchart showing a control method in the case where the operation of the compressor 1 is controlled depending on the hot water temperature, and this control method is explained hereinafter with reference to Figs. 5 and 6.

As shown in Fig. 5, the cold water temperature detector 34 is provided in the cold water tank 6 to control^' the feed water operation of the hot and cold water dispenser depending on the cold water temperature detected by the cold water temperature detector 34..

As shown in Fig. 6, in order to avoid a freeze of cold water in the cold water tank 6, the controller 14 determines at step S11 whether the cold water temperature Tc in the cold water tank 6 is less than a lower limit temperature (for example, 1⁰C), and if the former is less than the latter, the valve 13 is opened at step S12 so that the first feed water control for feeding water of a room temperature in the feed water tank 30 is conducted to increase the cold water temperature in the cold water tank 6. At step S13, a determination is made whether the temperature Tc detected by the cold water temperature detector 34 is greater than a set temperature (for example, 2⁰C) higher than the lower limit temperature. If the determination at step S13 is YES, the valve- 13 is closed at step S14 to stop water feed from the feed water tank 3,0, and the procedure proceeds to step S15. Furthermore, if the cold water temperature Tc in the cold water tank 6 is greater than or equal to. the lower limit temperature at step S11 , or if the cold water temperature Tc detected by the cold water temperature detector 34 is less than or equal to the set temperature at step S 13, the procedure also proceeds to step S15. At step S 15, a determination is made whether the water level Hc in the cold water tank 6 detected by the level detector 38 is higher than an upper limit level.

If the water level Hc, is higher than the upper limit level, the cold water circulating pump 36 is operated at step S16 so that the second feed water control for returning cold water in the cold water tank 6 to the feed water tank 30 is conducted, thereby preventing an overflow from the cold water tank 6 that may be caused by water feed from the feed water tank 30 to the cold water tank 6.

At step S17, a determination is made whether the water level Hc in the cold water tank 6 is lower than a set level that is lower than the upper limit level, and if the former is lower than the latter, the operation of the cold water circulating pump 36 is stopped at step S18, and the procedure returns to step S11.

Furthermore, if a determination has been made at step S15 that the water level Hc in the cold water tank 6 is lower than or equal to the upper limit level, or if a determination has been'made at step S17 that the water level Hc in the cold water tank 6 is higher than or equal to the set level, the procedure also returns to step SH .

According to the second embodiment of the present invention referred to above, even if the operation Of the refrigerating cycle is controlled depending on a tank having a higher load, i.e., either hot or cold water that is. used more, a relatively simple feed water control can realize a hot and cold water dispenser capable of supplying hot and cold water in a practically permissible temperature range.

Although the construction of Fig. 3^'is intended for the hot water control, while the construction of Fig. 5 is intended for the cold water control, both the hot water control and the cold water control can be conducted simultaneously. In this case, only one pump can be commonly used for the hot water circulating pump 32. and the cold water circulating, pump 36, making it possible to simplify the piping arrangement. ^• Embodiment s. • Fig. 7 depicts a refrigerating cycle of a hot and cold water dispenser according to a third embodiment of the present invention, and Figs. 8A and 8B depict flowcharts showing a method of controlling the same.

The construction shown in Fig. 7 is the same as that shown in Fig. 1 in the refrigerant to^' be used in the refrigerating cycle and the like, but differs therefrom in the following points.

As shown in Fig. 7, the refrigerating cycle includes a first refrigerant bypass line 41 having an auxiliary radiator 40^' in parallel with the radiator 2 and a second refrigerant bypass line 43 having an auxiliary evaporator 42 in parallel with the evaporator 4. The hot water tank 5 and the cold water tank 6 are. connected to the feed water tank 30 via the feed water lines 7, 8, respectively, and have the hot water temperature detector 33 and the cold water temperature detector 34 accommodated therein, respectively. The refrigerating cycle also includes a 5 plurality of changeover valves 50, 51 , 52, 53 (hereinafter referred to simply as valves) for switching a refrigerant flow in the refrigerating cycle.

The control method for the hot and cold water dispenser of Fig. 7 is explained hereinafter with reference to the flowcharts of Figs. 8A and 8B. i I,

Fig. 8A depicts the flowchart for the hot water control . and particularly

/ 10 depicts the case where the hot water temperature in the hot water tank 5 is ^{1 '} maintained between a first set temperature (for example, 60⁰C) and a second set temperature (for example, ^'70⁰C) higher than the first .set temperature.

At step S21 , the controller 14 determines whether the hot water temperature Th detected by the hot water temperature detector 33 is less than the- 15 first set temperature, and if the former is less than the latter, the valve 50 is opened and the valve 51 is closed at step S22 so that the hot water in the hot water tank 5 may be heated by the refrigerant that flows through the .radiator 2. In such a state, the refrigerating cycle is operated for a predetermined period of time, and at step S23, a determination is made whether the hot water temperature Th is greater than 20 the second set temperature. If the hot water temperature Th is greater than the second set temperature, the valve 50 is closed and the valve 51 is opened at step S24 so that the refrigerant may flow through the first refrigerant bypass line 41 having the auxiliary radiator 40, and the procedure returns to step S21.

If a determination has been made at step S21 that the hot water

25 temperature Th is greater than or equal to the first set temperature, the^' procedure proceeds- to step S24, while if a determination has been made at step S23 that the hot water temperature Th is less than or equal to the second set temperature, the determination at step S23 is repeatedly carried out. On the other hand, Fig. 8B depicts the flowchart for the cold water control and particularly depicts the case where the cold water temperature in the cold water tank 6 is maintained between a third set temperature (for example, 6⁰C) and a fourth set temperature (for example, 4°C) lower than the third set temperature. ^' At step S3T, the controller 14 determines whether the cold' water temperature Tc detected by the cold water temperature detector 34 is greater than the third set temperature, and if the former is greater than the latter, the valve 52 is

^• opened and the vaive 53 is closed at step S32 so that the cold water in the cold water tank 6 may be cooled by the refrigerant that flows through the ^"evaporator 4. In such a state, the refrigerating cycle is operated for a predetermined_^period of time, and at step S33, a determination is made whether the cold water temperature Tc is less than the fourth set temperature. If the cold water temperature Tc is less than the fourth set temperature, the valve 52 is closed and the valve 53 is opened at step

S34 so that the refrigerant may flow through the second refrigerant bypass line 43 having the auxiliary evaporator! 42 so as not to further cool the cold water, and the procedure returns to step S31. ^{: '}

If a determination has been made at step S31 that the cold water temperature Tc is less than or equal to the third set temperature, the procedure proceeds to step S34, while if a determination has been made at step S33 that the cold water temperature Tc is greater than or equal to the fourth set temperature, the determination at step S33 is repeatedly carried out. -

In this way, the hot water temperature and the cold water temperature can be controlled within respective optimum temperature ranges by controlling a refrigerant flow to the auxiliary radiator 40 or to the auxiliary evaporator 42. In addition, the high pressure or the low pressure in the refrigerating cycle can be optimized.

It is to be noted here that although in the above-described embodiment the hot water temperature control and the cold water temperature control are controlled separately, the hot water temperature control and the cold water temperature control can be interlocked with each other.

. It is further to be noted that although in the above-described embodiment the refrigerant flow is switched by selectively opening or closing a plurality of changeover valves, a lesser number of three-way valves or the like may be used as the changeover valves.

It is also to- be noted that although the first refrigerant bypass line 41 having the auxiliary radiator 40 is provided in parallel with the radiator 2, while the second refrigerant bypass line ^'43 having the auxiliary evaporator 42 is provided in parallel with the evaporator 4, either one of the first or second refrigerant bypass line

41 , 43 may be provided. ^'

Fig. 9 depicts a refrigerating cycle of a modification of the hot and cold water dispenser according to the above-described embodiment, and Figs. 1 OA and 1 OB depict flowcharts showing a method of controlling the same. The refrigerating cycle shown in Fig. 9 differs from that shown in Fig. 7 in that the former is provided with a first fan 54 for cooling the auxiliary radiator 40 and a second fan 55 for cooling the auxiliary evaporator 42.

The control method for the hot and cold water dispenser of Fig. 9 is explained hereinafter with reference to the flowcharts of Figs. 10A and 10B. Fig. 10A depicts the flowchart for the hot water control and particularly

^•depicts the case where the hot water temperature in the hot water tank 5 is maintained -between a first set temperature (for example, 60°C) and a second set temperature (for example, 7O⁰C) higher than the first set temperature.

At step S41, the controller 14 determines whether the hot water temperature Th detected by the hot water temperature detector 33 is less than the first set temperature, and if the former is less than the latter, the valve 50 is opened and^'the valve 51 is closed at step S42 so that the hot water in the hot water tank 5 may be heated by the refrigerant that flows through the radiator 2. In contrast, if the hot water temperature Th detected by the hot water temperature detector 33 is greater than or equal to the first set temperature, the determination at step S41 is repeatedly carried out. In such a state, the refrigerating cycle is operated for a predetermined period of time, and at step S43, a determination is made whether the hot water temperature Th _.is less than a third set temperature (for example, 50⁰C) that is less than the first set temperature. If the hot water temperature Th is greater than or equal to the third set temperature, the procedure proceeds to step S44 at which a determination is made whether the hot water temperature Th is greater than the second set temperature. If a determination has been made at step S44 that the hot water

-temperature Th is greater than the. second set _.temperature, the valve 50 is closed and the valve 51 is opened at step S45 so that the refrigerant may flow through the first refrigerant bypass line 41 having the auxiliary radiator 40, and the procedure returns to step S41. In contrast, if a determination has been made at step S44 that the hot water temperature Th is less than or equal to the second set temperature, the procedure returns to step S43.

Moreover, if a determination has been made at step S43 that the hot water temperature Th is. less than the third set temperature, a determination is made at step S46 whether the valve 52 is closed and the valve 53, is opened, i.e., whether the cold water tank 6 is not being cooled because the hot water in the hot water tank 5 must be rapidly heated. If the cold water in the cold water tank 6 is being cooled, the procedure returns to step S43, and if the cold water in the^' cold water tank 6 is not being cooled, the procedure proceeds to step S47 at which the second fan 55 is operated. The operation of the second fan 55 considerably enhances the refrigerating capacity of the auxiliary evaporator 42 and, hence, the radiating capacity of the radiator 2 is similarly considerably enhanced, making it possible to rapidly heat the hot water in the hot water tank 5.

At step S48, if a determination has been made that the hot water temperature Th is greater than the third set temperature or the cold water temperature Tc is greater than a fourth^' set. temperature (for example, 6⁰C) (the state in which the cold water tank 6 is being cooled), the operation of the second fan 55 is stopped at step S49, and the procedure returns to step S43. If a determination has been made at step S48 that the hot water temperature Th is less than or equal to the third set temperature or the cold water temperature- Tc is less than or equal to

■ the-fourth set temperature, ^'the determination at step S48 is repeatedly carried out.

On _. the other hand, Fig. 1 OB depicts the flowchart for the cold water control and particularly depicts the case where the cold water temperature in the cold water tank 6 is maintained, between a fourth set temperature (for example, 6⁰C)

^■ and a fifth set. temperature (for example, 4°C) lower than the fourth set temperature.

At step S51 , the, controller 14 determines whether the cold water temperature Tc detected by the cold water temperature detector 34 is greater than the fourth set temperature, and if the former is greater than the latter, the valve 52 is opened and the valve 53 is closed at step S52 so that the cold water in the cold water tank 6 may be^' further cooled by the refrigerant that flows through the evaporator 4. In contrast, if the cold water temperature Tc detected by the cold water temperature detector 34 is less than or equal to the fourth set temperature, the determination at step S51 is repeatedly carried out. In ^■ such a state, the refrigerating cycle is operated for a predetermined period of time, and at step S53, a determination is made whether the cold water temperature Tc is greater than a sixth set temperature (for example, 1 O⁰C) that is greater than the fourth set temperature. If the cold water temperature Tc is less than or equal to the sixth set temperature, the procedure proceeds to step S54 at which a determination is made whether the cold water temperature Tc is less than the fifth set temperature.

If a determination has been made at step S54 that the^' cold water temperature Tc is less than the fifth set temperature, the valve 52 is closed and the valve 53 is opened at step S55 so that the refrigerant may flow through the second refrigerant bypass line 43 having the auxiliary evaporator 42 so as not to further cool the cold water in the cold water, tank 6, and the procedure returns to step S51. In contrast, if a determination has been made at step S54 that the cold water temperature. Tc is greater than or equal to the fifth set temperature, the procedure returns to step S53.

Moreover, if a determination has been made at step S53 that the cold water temperature Tc is greater than the sixth set^' temperature, a determination is made at step S56 whether the valve 50 is closed and the valve 51 is opened, i.e., whether the hot water tank 5 is not being heated because the cold water in the cold water tank 6 must be rapidly cooled. If the hot water in the hot water tank 5 is being heated, the procedure returns to step S53, and if the hot water in the hot water tank 5 is not being heated, the procedure proceeds to^' step S57 at which the first fan 54 is operated. The operation of the first fan 54 considerably enhances the

^■ radiating capacity of the auxiliary radiator 40 and, hence, the refrigerating capacity of the evaporator 4 is similarly considerably enhanced, making it possible to rapidly cool the cold water in the cold water tank 6.

At step S58, if a determination has- been made that the cold water temperature Tc is less than the sixth set temperature or the hot water temperature Th is less than the first set temperature (the state . in which the hot water tank 5 is being heated), the operation of the first fan 54 is stopped . at step S59, and the procedure returns to step S53. If a determination has been made at step S58 that the cold water temperature Tc is _.greater than or equal to the sixth set temperature or the hot water temperature Th is greater than or equal to the first set temperature, the determination at step S58 is repeatedly carried out. Fig. 11 depicts a refrigerating cycle of another modification of the hot and cold water dispenser according to the above-described embodiment, and Fig. 12 depicts a flowchart showing a method of controlling the same.

The refrigerating cycle shown in Fig. 11 differs from that shown in _. Fig.

1.7 7 in that the former is not .provided with the second refrigerant bypass line that is connected in parallel with the evaporator 4 in the latter, but is provided with an auxiliary heater 54 accommodated in the hot water tank 5.

That is, the refrigerating cycle of Fig. 11 is intended to preferentially control the cold water temperature by appropriately controlling the compressor 1 depending on the cold water temperature and to control the hot water temperature by selectively operating the auxiliary heater 54 and the auxiliary evaporator 40 provided on the first_, refrigeranfrbypass line 41.

More specifically, the flowchart of Fig. 12 shows the case where the cold water temperature in the cold water tank 6 to be preferentially controlled is maintained between a first set temperature (for example, 6°C) and a second set temperature (for example, 4°C) lower than the first set temperature, while the hot water temperature in the hot water tank 5 is maintained between a third set temperature (for example, 60⁰C) and a fourth set temperature (for example, 70⁰C) higher than the third set temperature.

At step S61 , the controller 14 determines whether the cold water temperature Tc in the cold water tank 6 is greater than the first set temperature, and if the former is greater than the latter, the refrigerating cycle is operated by operating the compressor 1 at step S62 with the auxiliary heater 54 kept off. At step S63, a determination is made whether the hot water temperature Th in the hot water tank 5 is- less than the third set temperature, and if the former is less than the latter, the valve 50 is opened and the valve 51 is closed at step S64 so that the hot water in the hot water tank 5 may be further heated by the refrigerant that flows through the radiator 2. In such a state, the refrigerating cycle is operated for a predetermined period of time, and at step S65, a determination is made whether the hot water temperature Th is greater than the fourth set temperature. If the hot water temperature Th is greater than the fourth set temperature, the valve 50 is closed and the valve 51- is opened at step S66 so that the refrigerant may flow through the .first refrigerant bypass line 41 having the auxiliary radiator 40, and the procedure proceeds to step S67.

^• If a determination has been made at step S63 that the hot water temperature Th in the hot water tank 5 is greater than or equal to the third set temperature, the procedure proceeds to step S66, while if a determination has been

^" made at step S65 that- the hot water temperature Th is less than or equal to the fourth set temperature, ^■ the , procedure proceeds to step S67 at which a determination is made whether the cold water temperature Tc in the cold water tank

6 is less than the second set temperature. If the former is less than the latter, the operation of the compressor 1 is stopped at step S68, while if not, the procedure returns to step S63.

Furthermore, if a. determination has been made at step S61 that. the cold water temperature Tc in the cold water tank 6 is less than. or equal to the first set temperature, the operation of the compressor 1 is also stopped at step S68. At step S69, a determination is made whether the hot water temperature Th in the hot water tank 5 is less than the third set temperature, and if the former is less than the latter, the auxiliary heater 54 is operated at step S70 and the procedure returns to step S61. On the other hand, if a determination has been made at step S69 that the hot water temperature Th in the hot water tank 5 is greater than or equal to the third set temperature, the procedure also returns to step

S61.

As shown in Fig. 12, the cold water temperature in the cold -water tank 6 and the hot water temperature in the hot water tank 5 can be both appropriately controlled by the ON/OFF control of the compressor 1 , the ON/OFF control of the auxiliary heater 54, and the opening and closing control of the refrigerant passage changeover valves 50, 51. Industrial Applicability

The present invention can provide a hot and cold water dispenser capable of supplying cold water and hot water of a high temperature by making use of a refrigerating cycle in which a refrigerant that is inexpensive, safe, and gentle with the environment is used. The hot and cold water dispenser according to the present invention is also superior in power-saving nature and is, hence, useful as a hot and cold water dispenser for domestic or business use.

Claims

CLAIMS 1. A hot and cold water dispenser comprising: a compressor, a¹ radiator, a pressure-reducing ^mechanism, and an evaporator all connected in series to define a refrigerating cycle, in which a refrigerant that operates in a supercritical state is filled; a hot^' water dispenser for supplying hot water that is heated by the radiator; and a cold water, dispenser for supplying cold water that is cooled by the evaporator.

2. . The hot and cold water dispenser according to claim 1 , wherein the refrigerant is carbon dioxide.

3. The hot and cold water dispenser according to claim 1 , wherein the hot water dispenser comprises^' a hot water tank in which the ^' radiator is accommodated, while the cold water dispenser comprises a cold water tank in which the evaporator is accommodated. -

4. The hot and cold water dispenser according to claim 3, further comprising a feed water tank for supplying water to both the hot water .tank and the cold water tank.

5. The hot and cold water dispenser according to claim 4, further comprising a first feed water line for supplying water from the feed water tank to the hot water tank, a second feed water line for. supplying water from the feed water tank to the cold water tank, and a third feed water line for supplying hot water or cold water from one of the hot water tank and the cold water tank to the feed water tank.

6. The hot and cold water dispenser according to claim 5, further comprising a temperature detector for detecting a water temperature in one of the hot water tank and the cold water tank, wherein water feed control to the feed water tank is conducted depending on the water temperature detected by the temperature detector.

7. The hot and cold water dispenser according^' to claim 6, further comprising a level detector accommodated in one of the. hot water tank and the cold water tank for detecting a water level in the tank, wherein water level control of one of the hot water tank and the cold water tank is conducted depending on the water level detected by the level detector.

8. The hot and cold water dispenser according to claim 4, further ^' comprising a refrigerant bypass line having an auxiliary radiator in parallel with the radiator and a hot water temperature detector for detecting a hot water temperature in the hot water tank, wherein hot water temperature control is conducted depending on the hot water temperature detected by the hot water temperature detector.

9. The hot and cold water dispenser, according to claim 8, further comprising an auxiliary heater accommodated in the hot water tank, wherein the auxiliary heater is controlled depending^' on the hot water temperature detected by the hot water temperature detector.

10. The hot and cold water dispenser according to claim 8, further comprising a fan for cooling the auxiliary radiator.

11. The hot and co|d water dispenser according to claim 4, further comprisingva refrigerant bypass line having an auxiliary evaporator in parallel with the evaporator and a- cold water temperature detector for detecting a cold water temperature in the cold water tank, -wherein cold water temperature control is conducted depending on the cold water temperature detected by the cold water temperature detector.

12. The hot and coid water dispenser according to claim 11 , further comprising a fan for cooling the auxiliary evaporator.

13. The hot and coid water dispenser according to claim 4, further comprising a first refrigerant bypass line having an auxiliary radiator in parallel with the radiator, a hot water temperature detector for detecting a hot water temperature in the hot . water tank, a second refrigerant bypass line having an auxiliary evaporator in parallel with the evaporator, and a cold water temperature detector for d^'etecting a cold water temperature in the cold water tank, wherein hot water temperature control is conducted depending on the hot water temperature detected by the hot water temperature detector, while cold water temperature control is conducted depending on the cold water temperature detected by the cold water temperature detector.

14. The hot and cold water dispenser according to claim 13, further comprising a fan for cooling the auxiliary radiator and another fan for cooling the ^' auxiliary evaporator.

15. A method of controlling a hot and cold water dispenser that comprises a compressor, a radiator, a pressure-reducing mechanism, and an evaporator all connected in series to define a refrigerating cycle, in which carbon dioxide is filled as a refrigerant; a hot water tank having the radiator accommodated therein; a cold water tank having the evaporator accommodated therein; and a feed water tank for supplying water to one of the hot water tank and the cold water tank, said method comprising: detecting one of a hot water temperature in the hot water tank and a cold Water temperature in the cold water tank; supplying water from the feed water tank to one of the hot water tank and the cold water tank depending on the detected temperature; and supplying one of hot water in the hot water tank and cold water in the cold water tank to the feed water tank.

16. ^■ The method according to claim 15, wherein if the hot water temperature in the hot water tank is greater than a predetermined value, water in the feed water tank is supplied to the hot water tank.

17. The method according to claim 16, wherein if a water level in the hot water tank is greater than a predetermined level, hot water in the hot water tank is supplied to the feed water tank.

18. . The method according to claim 15, wherein if the cold water temperature in the cold water tank is less than a predetermined value, water in the feed water tank is supplied to the cold water tank.

19. The method according to claim 18, wherein if a water level in the cold water tank is greater than a predetermined level, cold water in the cold water tank is supplied to the feed water tank.

20. The method according to claim 15, wherein the hot and cold water dispenser further comprises a- first refrigerant bypass line^' having an auxiliary radiator in parallel with the radiator and a second refrigerant bypass line having an auxiliary evaporator in parallel with the evaporator, and further comprising switching a refrigerant passage to the first refrigerant bypass line or the second refrigerant bypass line depending on the detected water temperature.

21. The method according to claim 20, wherein if a hot water temperature in the hot water tank is greater than a predetermined value, the refrigerant is caused to flow through the first refrigerant bypass line.

22. The method according to claim 20, wherein if a cold water temperature in the cold water tank is less than a predetermined value, the refrigerant is caused to flow through the second refrigerant bypass line.

23. The method according to claim 20, wherein the auxiliary radiator and the auxiliary evaporator have respective cooling fans, and if the refrigerant passage has been switched to the first refrigerant bypass line or the second refrigerant bypass line, an associated one of the cooling fans is operated.