JPH10108818A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove surely even oils and fats mixed with drain hot water and deposited to a heat exchanging pipe. SOLUTION: A pipe-like evaporator 27 of a constituent of a heat pump is disposed in a drain hot water recovering tank 30 to store the drain hot water from a tableware washing machine 1. A bypass pipe is connected between the high pressure side of a compressor 24 and an inlet of the evaporator 27 where an opening/closing hot gas valve 62 is interposed. A temperature sensor 64 is set in the outlet side of the evaporator 27. In the completion of heat recovery, the running of the compressor 24 is continued while the hot gas valve 63 is opened and hot gas is supplied to the evaporator 27 so that the evaporator 27 is heated from the inside to liquefy an oil and fat film deposited on the surface. At the same time a shunt valve 54 is opened and the residue of warm water formed in the part of a condenser 25 is sprayed toward the evaporator 27 and flushed away. When the evaporator 27 is heated to a predetermined temperature, the supply of hot gas is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for raising the temperature of a fluid such as water or a refrigerant fed to a feed pipe by utilizing the heat of waste water. The present invention relates to a heat exchange device capable of reliably removing fats and oils adhering to a feed pipe when mixed.

[0002]

2. Description of the Related Art In the field of dishwashers, for example, in order to save energy and reduce running costs, the temperature of newly supplied rinsing water is increased by utilizing the heat of hot water after rinsing is completed. That is being done. Specifically, in the tank that stores the hot water from the dishwasher,
A feed pipe for feeding raw water of rinsing water is provided, and heat is exchanged with hot water to increase the temperature while feeding the raw water to the feed pipe. On the other hand, the hot water discharged from the dishwasher contains food residues and the like, and if it adheres to the feed pipe, there is a problem that heat exchange performance is deteriorated. As a conventional cleaning means, physical means such as spraying water on the surface of the feed pipe or rubbing with a brush has been generally used.

[0003]

However, in the conventional method, general dirt such as food residue can be removed, but if grease such as lard adheres, it cannot be easily removed. . Such adhering fats and oils not only perish easily, but also cause deterioration of heat exchange performance. The present invention has been completed based on the above demands, and an object of the present invention is to make it possible to reliably remove even if fats and oils adhere to a feed pipe.

[0004]

In order to achieve the above-mentioned object, the present invention is directed to a heat exchanger in which a fluid supply pipe is provided in a tank for storing waste water so as to be able to exchange heat. The present invention is characterized in that there is provided a means for supplying a high-temperature fluid to the feed pipe. Further, the invention according to claim 2 includes a heat pump having a refrigeration cycle configured by connecting a compressor, a condenser, an expansion valve, and an evaporator with piping and sealing a refrigerant. In a heat exchange device disposed in a tank for storing waste water and recovering the heat of the waste water by a refrigerant flowing through an evaporator, a heat exchanger is provided between a high pressure side of the compressor and an inlet of the evaporator. , A bypass path provided with an on-off valve is provided,
It is characterized in that hot gas on the high-pressure side of the compressor can be supplied to the evaporator through the bypass passage with opening of the on-off valve. According to a third aspect of the present invention, in the second aspect of the invention, raw water supplied to a water supply pipe is heated by the condenser part of the heat pump to generate hot water, and Is characterized in that a structure is provided in which water spraying means is provided to allow the heated warm water to be sprayed toward the evaporator.

[0005]

Actions and effects of the present invention

<Invention of claim 1> When the high-temperature fluid is fed to the feed pipe when the heat exchange between the hot water and the fluid is completed, the feed pipe is heated from the inside and sticks to the surface. The oil film is liquefied and removed by dropping into a tank or the like. This keeps the surface of the feed pipe clean, prevents rot and improves heat exchange performance. <Invention of claim 2> When the temperature of the refrigerant flowing through the evaporator of the heat pump is increased by exchanging heat with the hot water discharged from the dishwasher,
Since the evaporator is quenched in function, the oil and fat mixed in the hot water tends to stick to the surface of the evaporator. Therefore, at the end of heat exchange, for example, when the on-off valve of the bypass passage is opened and hot gas discharged from the compressor is supplied to the condenser, the evaporator is heated from the inside, and the oil film is liquefied, It is removed by dropping or the like, and the surface of the evaporator is kept clean. <Invention of claim 3> By spraying hot water toward the evaporator by the water spraying means at the time of heating the evaporator or the like, it is possible to more reliably remove fats and oils.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
7 will be described with reference to FIG. Here, in the case where hot water for rinsing used in the dishwasher is generated by a hot water generator equipped with a heat pump, a refrigerant flowing through an evaporator portion of a refrigeration cycle constituting the heat pump,
The example which applied this invention to the part which heat-exchanges with the hot water from a dishwasher is shown. In FIG. 1, reference numeral 1 denotes a dishwasher, on the side of which a hot water generator 20 equipped with a heat pump 21 is installed. First, the structure of the dishwasher 1 will be described. A washing chamber 2 for accommodating tableware through a rack (not shown) is formed in an upper part of the inside thereof. A pair of cleaning nozzles 3 and rinsing nozzles 4 are provided on the lower surface side. On one side of the bottom surface of the cleaning chamber 2, a cleaning tank 6 for storing cleaning water mixed with an alkaline detergent is formed, and the cleaning water stored therein is pumped up by a cleaning pump 7 and the cleaning nozzle 3 described above. Are sprayed toward tableware, and then circulated and supplied to the washing tank 6.

Below the washing tank 6, a hot water storage tank 8 for storing hot water for rinsing is provided. In the hot water storage tank 8, the hot water generator 2
0 is supplied to the hot water supply pipe 1 provided with the hot water supply valve 9.
0 and stored. The stored hot water is pumped up by the rinsing pump 11, is jetted from the rinsing nozzle 4 toward the tableware, and is collected in the washing tank 6. The washing tank 6 is provided with an overflow pipe 13. The overflow pipe 13 takes in the overflowed hot water from the washing tank 6,
The hot water is discharged through a drain pipe 14 into a waste water recovery tank 30 provided in the hot water generator 20. In addition,
The heater 1 is provided in the cleaning tank 6 and the hot water storage tank 8, respectively.
Thermostats 5 and 16 and a thermostat (not shown) are provided so that the temperature of the washing water is maintained at about 60 ° C. and the temperature of the rinsing water is maintained at about 80 ° C. That is, the dishes are in the washing room 2
When washing is performed, washing water is sprayed from the washing nozzle 3 to wash the dishes, and subsequently, hot water is sprayed from the rinsing nozzle 4 to perform rinsing. The discharged hot water that has not been collected in the washing tank 6 and overflowed is collected by the hot water generator 20.
The exhausted heat is discharged to the side, and the recovered heat is exchanged with raw water such as tap water supplied to the water supply pipe 10 to generate hot water, which is supplied to the hot water storage tank 8 described above. It is supposed to be.

Next, the hot water generator 20 will be described. The hot water generator 20 includes a heat pump 21 and is housed in a box-shaped casing 22. As shown in FIG. 6, the heat pump 21 includes a compressor 24, a condenser 25, an expansion valve 26, and an evaporator 2.
7 is circulated therein and contains therein a refrigerant Freon gas (R
-22) constitutes a refrigeration cycle by being enclosed in a flowable manner. The compressor 24 is relatively large and is installed on the bottom surface in the casing 22 as shown in FIGS. A cover plate 31 is provided beside the compressor 24.
An attached hot water recovery tank 30 is provided.

As shown in FIGS. 4 and 5, a pipe-shaped evaporator 27, which is a component of the refrigeration cycle, is spirally wound along the inner peripheral surface of the hot water recovery tank 30. The entrance 27a and the exit 27b are
1 and connected to the refrigerant pipe 21a. A drainage inlet 32 is provided on one side of an upper part of the drainage recovery tank 30, and the drainage pipe 14 drawn out of the overflow pipe 13 of the washing tank 6 in the dishwasher 1.
, And the hot water overflowing from the washing tank 6 can be introduced. On the other side, a discharge port 33 for discharging the overflow water of the waste water recovery tank 30 itself is provided, and a drain pipe 34 is connected. As shown in FIG. 5, a propeller-like agitator 36 is provided in the waste water recovery tank 30 so as to be located at a substantially central height inside the evaporator 27. 3
1 is driven to rotate via a shaft 38 by a drive motor 37 provided on the drive motor 1. A drain valve 40 is provided on the bottom surface of the waste water recovery tank 30.
The drain valve 40 is a normally-open type, and opens and closes at the tip of a rod 41 that is freely movable up and down through the cover plate 31, and contacts and separates from the upper surface side of a valve port 42 opened at the bottom surface. A valve element 43 is provided, and the rod 41 is always urged upward by a spring member 44 so that the valve element 43 as shown by a chain line in FIG.
Is lifted to open the valve port 42 and the cover plate 3
As shown by the solid line in FIG. 1, the valve port 42 is closed by pushing down the rod 41 and the valve body 43 against the urging force by the exciting force of the solenoid 46 mounted on the bracket 1 via the bracket 45. Has become. This drain valve 4
Numeral 0 is connected to the above-mentioned drain pipe 34 in a merged manner. The lid plate 31 of the hot water recovery tank 30 is provided with two watering nozzles 48 for spraying hot water toward the evaporator 27 to wash it.

The condenser 25 is formed in the shape of a large-diameter pipe, in which a water supply pipe 10 for supplying raw water for rinsing water is provided.
Double tube part 2 through which the middle part is inserted to enable heat exchange
8 are formed. As shown in FIGS. 2 and 3, the double pipe portion 28 is stretched while turning around the inside of the two side surfaces of the casing 22. The outlet side of the water supply pipe 10 is connected to the hot water storage tank 8 of the dishwasher 1 as described above. The expansion valve 26 is of a temperature type having a temperature-sensitive cylinder 26a (see FIG. 6). A control box 49 containing a device for controlling the refrigeration cycle of the heat pump 21 and water supply and drainage is provided in the casing 22.
Is provided.

Referring to FIG. 6, the refrigeration cycle will be described. A bypass pipe 51 for pressure control is provided between a high pressure side and a low pressure side of the compressor 24, and a capacity adjusting valve 52 is provided therein. When the heat load (heat source) is insufficient or when there is no heat supply at the time of initial hot water supply, the capacity adjusting valve 52 bypasses the high-pressure hot gas to the low-pressure side, and the pressure on the low-pressure side is excessively reduced. It works to prevent you from doing so. An automatic water supply valve 53 is provided in the water supply pipe 10 at a position protruding from the double pipe section 28. The automatic water supply valve 53 functions to detect the pressure on the high pressure side, adjust the water supply amount accordingly, and keep the pressure on the high pressure side constant. Along with this, it is possible to take out hot water having a substantially constant temperature. On the upstream side of the automatic water supply valve 53 in the water supply pipe 10, a watering hose 55 provided with a flow dividing valve 54 is connected in a branched manner, and the watering hose 55 is provided on the cover plate 31 of the above-described wastewater recovery tank 30. Connected to the sprinkling nozzle 48. This diverting valve 54 discharges warm water remaining in the double pipe section 28 by opening when the operation is stopped,
It is used for cleaning the evaporator 27 and functions to prevent a transient insufficiency of the condensation capacity at the start of operation.

A refrigerant pipe 21a on the outlet side of the condenser 25;
A first auxiliary heat exchange unit 57 is configured by closely connecting a portion of the raw water supply pipe 10 on the near side that enters the double pipe section 28 in parallel. The first auxiliary heat exchange unit 57 functions to preheat the raw water by causing heat exchange between the liquid refrigerant discharged from the condenser 25 and the raw water of the rinse water. In addition, the refrigerant pipe 21a on the downstream side of the portion forming the first auxiliary heat exchange unit 57 and the refrigerant pipe 21a on the outlet side of the evaporator 27 are similarly closely connected in parallel to form the second refrigerant pipe. An auxiliary heat exchange section 58 is configured. The second auxiliary heat exchange section 58 heats the low-temperature refrigerant that has passed through the evaporator 27 with the high-temperature liquid refrigerant that has flowed out of the condenser 25 to prevent a liquid return phenomenon to the compressor 24 particularly in the latter half of operation. It functions to suppress and increase the heat utilization efficiency.

A receiver 59 is provided in the refrigerant pipe 21a between the portion constituting the second auxiliary heat exchange section 58 and the expansion valve 26. The receiver 59 serves to store the liquid refrigerant when the refrigerant is overfilled or when the internal balance is lost and the liquid refrigerant becomes excessive, thereby preventing the liquid refrigerant from staying in the condenser 25. . A refrigerant solenoid valve 60 is interposed between the receiver 59 and the expansion valve 26. The refrigerant solenoid valve 60 functions to prevent high-pressure gas from leaking from the expansion valve 26 to the low-pressure side when the operation is stopped, and to maintain high pressure.

In this embodiment, another bypass pipe 62 is provided between the high pressure side of the compressor 24 and the inlet side of the evaporator 27 to bypass hot gas to heat the evaporator 27. The hot gas valve 63 is interposed there. The hot gas valve 63 is always closed, and is closed at a predetermined timing, for example, the heat pump 21.
The opening control is performed each time the operation cycle is completed. In addition, the evaporator 27 has an evaporator 27 at the outlet side.
Is provided, and when the temperature detected by the temperature sensor 64 exceeds a set temperature, for example, 60 ° C., the hot gas valve 63 is closed. In connection with the open / close control of the hot gas valve 63, the compressor 24 is continuously operated while the hot gas valve 63 is open, and the hot gas valve 63 receives the detection signal of the temperature sensor 64 and operates. When the valve is closed, the operation of the compressor 24 is also stopped.

The present embodiment has the above-described structure,
Subsequently, the operation will be described with reference to the timing chart of FIG. The cleaning operation is performed by the cleaning tank 6 of the dishwasher 1.
And the hot water storage tank 8 are performed from a state of full water. First, dishes to be washed are stored in a rack and accommodated in the washing room 2 (rack operation). When the rack operation is completed, a cleaning cycle is started, and a cleaning operation in which the cleaning water in the cleaning tank 6 is pumped up by the cleaning pump 7 and jetted from the cleaning nozzle 3 is performed for several tens of seconds. After a stop time (draining time) of about 5 seconds, a rinsing cycle is subsequently started, and a rinsing operation in which warm water in the hot water storage tank 8 is pumped up by the rinsing pump 11 and jetted out of the rinsing nozzle 4 is performed for 7 seconds. Done to the extent. Thereafter, a stop time of about 5 seconds (similarly, a draining time) is set, whereby one washing step is completed.

In the above description, when the rinsing cycle is started, the hot water supply valve 9 is opened by turning off the float switch provided in the hot water storage tank 8, and the compressor 24 is turned on and the heat pump 21 is turned on. Get up and running. At the same time, the refrigerant solenoid valve 60 is also opened. In addition, the solenoid 46 provided in the waste water recovery tank 30 is excited to close the normally open drain valve 40, and the agitator 36 is driven to rotate. The hot water overflowing from the washing tank 6 after the start of the rinsing cycle flows into the hot water recovery tank 30 with a slight delay, and the evaporator 27 actually starts absorbing heat only a few seconds later.

In the hot water recovery tank 30, the hot water overflowing from the washing tank 6 of the dishwasher 1 is taken in little by little (taking several tens of seconds). While the waste water is being taken in, the heat pump 21 is fully operated to supply the liquid refrigerant to the evaporator 27, and the waste water is agitated by the stirrer 36 to promote heat exchange and start absorbing heat. Since the time that can be actually absorbed is several tens of seconds, the expansion valve 26 having a relatively large flow rate (refrigeration capacity) is used, and a large amount of refrigerant is supplied immediately after the rise. During the heat absorption, the overflow from the washing tank 6 ends first,
The waste water recovery tank 30 becomes full. Although the heat absorption is further continued, when the refrigerant reaches the evaporator 27 sufficiently, the temperature detected by the temperature-sensitive cylinder 26a decreases and the expansion valve 26 starts to close. However, since the timing of the flow control of the expansion valve 26 is necessarily delayed, the liquid returns slightly. Therefore, the liquid is prevented from returning by being heated in the second auxiliary heat exchange section 58, and the heat utilization efficiency is also improved. During this time, the raw water of the rinse water sent to the water supply pipe 10 is preheated by the first auxiliary heat exchange unit 57,
The heat is exchanged with the refrigerant in the double pipe section 28 to increase the temperature, and the hot water is gradually supplied to the hot water storage tank 8 of the dishwasher 1 via the hot water supply valve 9.

When a predetermined amount of hot water accumulates in the hot water storage tank 8 and the float switch is turned on, the operation for exhaust heat recovery and hot water generation is completed, the refrigerant solenoid valve 60 is closed, and the drainage of the waste water recovery tank 30 is performed. With the valve 40 opened,
The stirrer 36 is stopped. As a result, the hot water in the hot water recovery tank 30 is discharged, and the discharged hot water is discharged as a vortex due to the inertial force, so that all the food residues mixed in the discharged hot water are discharged together with the vortex. On the other hand, since the evaporator 27 is rapidly cooled during the recovery of the exhaust heat, the oil and fat mixed in the waste water may remain on the surface of the evaporator 27. Therefore, the compressor 24 is continuously operated, and the hot gas valve 63 provided in the bypass pipe 62 is simultaneously operated.
Is released. Thereby, the hot gas discharged from the compressor 24 is supplied to the evaporator 27 through the bypass pipe 62, and the evaporator 27 is heated from the inside. The hot gas valve 63 is controlled to open until the temperature of the evaporator 27 reaches 60 ° C., and the evaporator 27 continues to be heated. Generally, the melting point of fat is 28-48 ° C for lard, about 35 ° C for beef tallow, 45-50 ° C for yogurt, and if the evaporator 27 is heated to 50 ° C or more, it will evaporate. The oil film adhered to the vessel 27 is liquefied. Further, the flow dividing valve 54 is opened at the same timing as when the hot gas valve 63 is opened, and the warm water remaining in the double pipe portion 28 is divided into the watering hose 55 side. The hot water is sprinkled from the water spray nozzle 48 of the hot water recovery tank 30 toward the evaporator 27, and the oil and fat floating on the surface of the evaporator 27 is washed away. An alkaline detergent mixed with the hot water also adheres to the surface of the evaporator 27, and when it is dried to a high concentration, the evaporator 2
However, the alkaline detergent is washed away by spraying the above-mentioned warm water. The removed fats and oils and the alkaline detergent are discharged from the drain valve 40. As described above, when the temperature of the evaporator 27 rises to 60 ° C. and is detected by the temperature sensor 64, the hot gas valve 63 is closed, the operation of the compressor 24 is stopped, and the melting operation by the hot gas is performed. Is stopped. As described above, the oil / fat melting operation using the hot gas is performed every time the operation for recovering exhaust heat and generating hot water by the heat pump 21 ends.

As described above, according to the present embodiment, the hot gas is caused to flow into the evaporator 27 after the completion of the heat recovery from the discharged hot water, so that the evaporator 27 is heated from the inside and sticks to the surface. The oil film is liquefied and the evaporator 2
By spraying the warm water toward 7, the oil and fat components are completely removed, the surface of the evaporator 27 is kept clean, rot is prevented, and the heat exchange performance can be improved. Also,
When the oil or fat is wiped with a brush, the oil or fat attached to the brush may be spoiled, but such a problem does not occur.

The melting operation of fats and oils by hot gas is as follows.
This is not limited to the case where the heat recovery by the evaporator 27 is completed as in the above-described embodiment. May be performed. Further, the timing of stopping the oil / fat melting operation may be stopped after a certain period of time is delayed by a timer after the temperature sensor 64 detects that the temperature of the evaporator 27 has risen to the set value, or may be stopped by the temperature detection. Instead, it may be stopped when the set time of the timer expires.

<Other Embodiments> The present invention is not limited to the embodiments described above with reference to the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition, various changes can be made without departing from the scope of the invention. (1) In the present invention, a feed pipe for feeding raw water of rinsing water is provided in a tank for collecting hot water from a dishwasher, and the hot water and heat are supplied while feeding the raw water to the feed pipe. The present invention can be similarly applied to a heat exchange device used for preheating raw water by exchanging. In this case, in order to melt the fats and oils attached to the feed pipe, steam or high-temperature water may be flowed through the feed pipe. (2) The present invention can be widely applied not only to the drainage of a dishwasher but also to a general apparatus for heat exchange using household wastewater containing oils and fats, such as a drain of a sink. It is.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall structure of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the hot water generator as viewed from above.

FIG. 3 is a sectional view seen from the front.

FIG. 4 is a cross-sectional view of the waste water recovery tank as viewed from above.

FIG. 5 is a sectional view seen from the front.

FIG. 6 is a refrigeration cycle diagram of a heat pump.

FIG. 7 is a timing chart during a cleaning operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Dishwasher 21 ... Heat pump 21a ... Refrigerant piping 24 ... Compressor 25 ... Condenser 26 ... Expansion valve 27
... Evaporator 28 ... Double tube 30 ... Hot water recovery tank 4
8 ... watering nozzle 54 ... diversion valve 55 ... watering hose 6
2: bypass pipe 63: hot gas valve 64: temperature sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F28G 9/00 F24H 1/00 631G

Claims (3)

[Claims] 1. A heat exchange device in which a fluid supply pipe is provided so as to be capable of exchanging heat in a tank for storing waste water, wherein a means for supplying a high-temperature fluid to the supply pipe is provided. And heat exchanger. 2. A heat pump comprising a refrigeration cycle by connecting a compressor, a condenser, an expansion valve, and an evaporator with piping and sealing a refrigerant, and using the evaporator of the heat pump to discharge hot water from a dishwasher. In a heat exchange device arranged in a tank for storing and recovering heat of waste water by a refrigerant flowing through an evaporator, an on-off valve is provided between a high pressure side of the compressor and an inlet of the evaporator. A heat exchange device comprising: a bypass passage interposed therebetween; and hot gas on a high pressure side of the compressor can be supplied to the evaporator through the bypass passage when the on-off valve is opened. 3. The raw water supplied to the water supply pipe by the condenser part of the heat pump is heated to generate hot water, and the heated water is supplied to the water supply pipe by the condenser. 3. The heat exchange device according to claim 2, further comprising water spraying means for spraying water toward the evaporator.