Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
  • F24D3/00—Hot-water central heating systems
  • F24D3/08—Hot-water central heating systems in combination with systems for domestic hot-water supply
  • F24D3/082—Hot water storage tanks specially adapted therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
  • F24H1/18—Water-storage heaters
  • F24H1/20—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes
  • F24H1/201—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes using electric energy supply
  • F24H1/202—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes using electric energy supply with resistances
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
  • F24D3/00—Hot-water central heating systems
  • F24D3/08—Hot-water central heating systems in combination with systems for domestic hot-water supply
  • F24D3/087—Tap water heat exchangers specially adapted therefore

Definitions

• the invention relates to a method for the heating and storage of water to be used for sanitary purposes and apparatus for implementing the said method, the said invention being particularly useful for the production of hot water to be used for sanitary purposes 4n small quantities such as for household use.
• All the water storage heaters have the following features in common: a low level of installed thermal power, a relatively large water reserve and a storage temperature which is much higher than the usage temperature.
• the main advantages of the water storage heaters are as follows:
• water storage heaters have the following disadvantages:
• the heating time required to restore the water reserve is a few hours, generally around 5 to 7 hours for an electric water heater, and generally half of that for gas water storage heaters;
• V.acc V.acc x (t.acc-t.h2o)/(t.ut ⁇ - t.h2 ⁇ ) but the actual volume available V. ut ⁇ .
• effcdi ⁇ be obtained by drawing the water from the water stored, at the temperature desired t.util, mixing it manually or with a thermostatic mixer, with the cold water from the mains at the temperature t.h2o, gradually decreasing the temperature. However, drawing the water in this way stops as soon as the water comes from the stored reserve, albeit hot, but at a temperature below the t.util.
• V.util.eff V.util.eff
• V.acc the ratio of V.util.eff to V.util is called the "mixing factor" is always less than 1. In practise, it is as if there were available, in fact, a storage tank which is smaller than the actual volume V.acc. This drawback is currently limited, but not eliminated, by designing the cold water input methods for the storage space suitably so that the mixing of the input water with the already heated water is limited. The smaller the storage tank is, the more fastidious the phenomenon becomes, as is the case of the water heaters with a capacity of 15-30 litres used for showers.
• Technicians in the field also know that when the average temperatures are equal, the less uniform the distribution of the temperature is in a storage tank, the greater the heat loss is.
• the instant water heaters generally have the opposite features to the storage heaters: a high level of installed thermal power, no water reserve and heating to the usage temperature. The main advantages of the instant water heaters are as follows:
• the temperature should be constant regardless of the flow rates, but in reality, the lower flow rates produce water with too high a temperature, or the going out of the flame. In fact, the burner cannot bear combustion at a power which is much lower than the maximum. If the control is run on the output temperature, hunting is noted with extremely low, but normal, flow rates.
• the water In gas water heaters, used for producing hot water for sanitary purposes, the water is generally heated mdirectly by the primary heating circuit. If the heating involves storage, the adjustment of the flame power can be an ON-
• the aim of this invention is to indicate a method for heating water to be used for sanitary purposes and an apparatus to implement this method so as to eliminate the problems described earlier with regards to both the storage heating apparatus and methods and the instant ones, mamtaining the merits of both kinds.
• the main aim of the present invention is to produce a water storage heater whose mixing factor, as described above, is one.
• a further aim of the present invention is to obtain an unlimited quantity of water, continuously, from a water storage heater.
• a still further aim of the present invention is to guarantee an accuracy in the regulation of the temperature of the water dispensed which is at least equal to that of the storage heaters.
• FIG. 1 shows, schematically, a gas boiler for household use fitted with a storage tank for hot water to be used for sanitary purposes.
• Figure 2 shows, schematically, the aforementioned storage tank in the heating mode with no water being drawn.
• Figure 3 shows, schematically, the storage tank in figure 2 in the instant heating mode during the hot water dispensing phase.
• Figure 4 shows, in a perspective view, a part of the boiler in figure 1.
• Figure 5 shows a lateral section of the storage tank in the previous figure.
• Figure 6 shows, schematically, an electric water heater according to the invention.
• number 1 denotes the heat exchanger between the flame and the primary circuit of the room heating
• 2 indicates the burner, 3 the regulator valve for the gas at the point at which it reaches the burner
• 4 denotes the primary circuit of the room heating
• 5 is the storage tank for water to be used for sanitary purposes, the said tank, in its turn, being divided into two zones: 5a outlet and 5b inlet
• 6 indicates the temperature check probe for the stored water
• 7 denotes the valve for switching the primary circuit 4 between the room heating function and the heating function for the water to be used for sanitary purposes
• 8 indicates the thermostatic mixer for regulating the temperature of the water to be used for sanitary purposes
• 9 denotes the collection area within the storage tank 5 for the water to be used for sanitary purposes which will go to the connected devices
• MR indicates the delivery flow of the heating circuit
• RR the return flow of the heating circuit
• IS denotes the inlet of water from the main water system to the storage tank 5
• US indicates the outlet of hot water to be used for sanitary purposes from the boiler going towards the connected devices
• GAS denotes the connection to the gas supply system.
• FIG 3 in addition to the areas or elements already indicated in the previous figures, there are arrows which represent the direction of the flow of water while hot water is being drawn from the tank.
• Figure 4 shows only elements that have already been described.
• Figure 5 shows only elements that have already been described.
• Figure 6 shows, in addition to the elements already described in the previous figures, the section of a heat exchanger 15.1, as an alternative to the exchanger 15.
• the exchanger 15.1 could be made of a pipes band or a battery of armoured electrical resistors.
• the water heating methods according to the present invention are now described as applied to a boiler for room heating and production of hot water for sanitary purposes fitted with a storage tank according to one possible embodiment of the invention.
• the storage tank 5 is a 'rucksack' kind, substantially prismatic in shape, and crossed with baffles 13 and 14 whose structural functions are known: the baffle 13 is also an element of the embodiment of the invention being described now.
• supposing there is a period in which no hot water is drawn using the probe 6 the temperature of the water in the storage tank 5 is checked. If this temperature is less than a pre-set value t.acc, e.g. 70°C, the deviator valve 7 switches its position so that the primary circuit 4 closes through the heat exchanger 15. Then the fluid in the primary circuit 4 enters the heat exchanger 15 through the inlet 16, it runs through the first part 15a, passes over the partial division baffle 13 of the heat exchanger, through the opening 18, through the second part 15b of the exchanger 15 from which it exits thought the outlet 17 to return to the heat exchanger 1. Naturally the heating of the fluid circulating in the primary circuit 4 can be achieved with any known method.
• t.acc e.g. 70°C
• the containment sleeve for the secondary fluid i.e. the containment fluid for the water to be used for quelary purposes
• the storage tank cover 5 in other words, the water for sanitary purposes must be allowed to circulate freely around all the surfaces of the heat exchanger 15 that are in contact with the primary fluid.
• the flow switch 11 detects the passing of the water and, consequently, with known methods, ensures that, through the exchanger 15 and according to the methods described above, the primary heating fluid circulates.
• the exchanger 15 must occupy all the section of the passage from zone 10 to 5.b and from zone 5. a. to 9. This is to prevent part of the water to be used for sanitary purposes by-passing the first and the second part 15. a and 15.b of the exchanger 15 while being drawn.
• the baffle 13 is designed to force the water for sanitary purposes to run along the whole tank 5 so that there are no stagnant areas in the water in the higher part of the tank, nor air pockets which cannot be removed by the tow of the water in transit.
• the thermal power of the heat exchanger 15, in its entirety, must be sufficient to guarantee the dispensing of the thermal energy required to ensure the hot water for sanitary purposes reaches the connected devices for an unlimited time and at the maximum usage temperature t.util envisaged, regardless of whether or not there is enough water at the temperature t.acc. in the storage tank.
• the rnniimum requisite for the heat exchanger 15 in the embodiment in this invention is that its second part 15.b has enough exchanging power alone to guarantee the water from the main water system which is passing across it during the drawing phases can be heated to a temperature not less than the usage temperature t.util.
• the water heating method just described obviously achieves the aims described earlier with the following advantages.
• the exchanger 15 has the thermal power typical of the instant heaters for household use, i.e. at least 10 - l lkW, the natural circulation due to the convective heat exchanges is extremely active, so much so that it causes very little stratification of the water, in other words, the temperature increases very uniformly throughout the whole tank 5.
• a first advantage is that there is less heat loss than with storage tanks with the same average temperature, but the distribution of the heat loss is less uniform.
• the mixing factor cannot be lower than 1, i.e.
• V.acc x (t.acc - t.h2o) / (t.util -t.h2 ⁇ ).
• the low level of stratification and the pre-heating of the mcoming water ensure the temperature of the outgoing hot water to be used for quelary purposes is more uniform than in the storage tanks which do not follow the teachings of the present invention. Consequently, it is much easier to keep the temperature of the hot water to be used by the connected devices constant, by means of a thermostatic mixer or, even more so, by manual mixing.
• the heating method just described in a preferred embodiment, in which the method is applied to a boiler which produces hot water and stores it, can undergo a number of application variations, some examples of which now follow:
• the heat exchanger 15 could be composed of a different kind of heat generator than the one described above and the storage tank could also have a more traditional form.
• the storage tank 5 is formed with two zones 5a (outlet) and 5b (inlet) as well as the first part 15a of the exchanger 15; the first part 15. a is necessary for the heating phase while no water is being drawn, in the particular embodiment of the tank 5 just described it is particularly beneficial when installed in a heating boiler, but otherwise, according to the essence of the present invention, the heater 15 could just as well be composed exclusively of one part, i.e. the part defined in this report as the second part 15.b, while the hot water outlet US from the storage tank 5, as just mentioned, could be positioned above, according to the traditional form illustrated schematically in figure 6.
• a gas water storage heater with great benefits could be designed with a combustion chamber and a fume shaft positioned horizontally in relation to the lower part of the storage tank 5.
• the construction methods for the said combustion chamber with the relative shaft are described sufficiently in Italian patents n° 1 182 951 granted on 05.10.1987 and n° 1 178 296 granted on 09.09.1987.
• Equally advantageous is an electric combined instant - storage water heater with a high power level (at least 10-1 lkW) in which, with reference to figure 6, there is a band of electrical resistors 15.1 in position with the inlet for the water from the main water system.
• the implementation of the heating methods according to the present invention in this kind of hot water generator actually eliminates the adjustment difficulties for the outgoing water completely since, as it is clear to any technician in the field, although the regulation of the electrical power supplied remains stepped, the storage tank 5 acts as a thermal stabilizer, enabling the temperature of the outgoing water US to be adjusted easily by means of thermostatic mixer.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Water Supply & Treatment (AREA)
• Heat-Pump Type And Storage Water Heaters (AREA)
• Cookers (AREA)
• Control Of Resistance Heating (AREA)
• Resistance Heating (AREA)
• Underground Structures, Protecting, Testing And Restoring Foundations (AREA)
• Commercial Cooking Devices (AREA)
• Massaging Devices (AREA)
• Sorption Type Refrigeration Machines (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11437199

Family Applications (1)

Country Status (10)

Cited By (2)

Families Citing this family (2)

Citations (4)

• 2000
  • 2000-03-03 IT IT2000AN000006A patent/IT1316723B1/it active
• 2001
  • 2001-02-28 AT AT01915301T patent/ATE315208T1/de not_active IP Right Cessation
  • 2001-02-28 HU HU0301079A patent/HUP0301079A2/hu unknown
  • 2001-02-28 WO PCT/EP2001/002225 patent/WO2001065186A1/en active IP Right Grant
  • 2001-02-28 ES ES01915301T patent/ES2256218T3/es not_active Expired - Lifetime
  • 2001-02-28 AU AU2001242438A patent/AU2001242438A1/en not_active Abandoned
  • 2001-02-28 CZ CZ20022816A patent/CZ20022816A3/cs unknown
  • 2001-02-28 EP EP01915301A patent/EP1261828B1/en not_active Expired - Lifetime
  • 2001-02-28 DE DE60116473T patent/DE60116473T2/de not_active Expired - Lifetime
  • 2001-02-28 PL PL01365117A patent/PL365117A1/xx not_active Application Discontinuation

Patent Citations (4)

Also Published As

Similar Documents

Legal Events