WO2009122455A1

WO2009122455A1 - Heat exchanger operating at different pressures

Info

Publication number: WO2009122455A1
Application number: PCT/IT2008/000222
Authority: WO
Inventors: Giuseppe Floris
Original assignee: Giuseppe Floris
Priority date: 2008-04-04
Filing date: 2008-04-04
Publication date: 2009-10-08

Abstract

The invention concerns a new heater comprising a tank for the refrigerant fluid (B, C), at least one compressor pump (E), at least one heat exchanger (G), at least one pressure reducing valve (H). The refrigerant fluid in the liquid phase is distributed on the bottom of the tank (B), while the refrigerant fluid in the gas phase is distributed in the upper part of the tank (C). The compressor (E) draws the refrigerant fluid in the gas phase from the upper part of the tank (C) and conveys it towards the heat exchanger (G). The compression of the refrigerant fluid in the heat exchanger (G) is obtained by placing a pressure reducing valve (H) in the outlet pipe of said heat exchanger (G). The fluid cooled by the heat exchanger (G), once it has passed beyond the valve (H), is saturated and compressed in a low pressure area and tends to become liquid again. Said refrigerant fluid is conveyed again towards the inside of the tank (B, C), from where it restarts its cycle.

Description

HEATEXCHANGER OPERATINGATDIFFERENTPRESSURES

DESCRIPTION

The present patent concerns the sector of heating systems with heat pump and in particular it concerns heat pumps using phase change fluid. Considering the continuous increases in energy costs and the provisions regarding sound and environmental pollution, the present patent aims to offer an alternative solution suitable for overcoming these drawbacks. The heating systems currently used are the following:

- gas oil burners for heating water circulating in radiator elements; - propane gas or LPG burners for heating water circulating in radiator elements;

- heat pumps.

The heat pump system is based on the system employed for refrigerating plants and its operation is divided in the stages described here below. Stage 1 - EXPANSION

The refrigerant fluid in the liquid state is introduced in the expansion valve, flows out in the coil or evaporator and expands immediately registering a decrease in pressure and temperature. Stage 2 - EVAPORATION After the expansion stage the refrigerant fluid has modified its pre-existing pressure-temperature balance and, since now its pressure is too low compared to the temperature, it must produce more gas in order to restore the pressure and the pre-existing balance. The evaporation, however, requires the supply of heat, which is taken from the environment around the evaporator coil, so that the temperature around said evaporator coil decreases consequently.

The fluid changes into a gas, but its pressure doesn't increase because the compressor continues to pump fluid in the gas state from the evaporator to convey it to the condenser coil under high pressure. The heat transferred from the environment to the evaporated fluid that has changed into a gas follows the gas in the high pressure circuit and reaches the condenser.

Stage 3 - COMPRESSION

This stage is necessary to transfer the collected heat, that is, the heat transferred from the environment to the evaporator, to the high pressure circuit of the condenser, and this heat is transferred to another environment and heats it.

When all the fluid in the gas state expanded in the coil has passed beyond the compressor towards the high pressure circuit, both pressure and temperature increase.

Stage 4 - CONDENSATION

The refrigerant fluid, under high pressure and therefore completely in the gas state, is conveyed into the condenser coil, where it is cooled by means of a water or air jet. The refrigerant fluid, which was in a balance condition at high temperature and high pressure, is now at high pressure and low temperature, and therefore it must change state again, that is, become a liquid, thus decreasing its own pressure.

The heat that is transferred to the water or air of the condenser should be the same as that taken from the environment by the evaporator coil. After the condensation stage, the fluid in the liquid state freely falls into the tank and is ready to return into the expansion valve and start its cycle again.

The operation of the heat pump takes place using an internal and an external heat exchanger.

To refrigerate the internal environment, the internal heat exchanger is used as an evaporator and the external heat exchanger as a condenser, while to heat the environment the fluid cycle is inverted: the internal heat exchanger operates as a condenser and the external exchanger operates as an evaporator.

This process requires much energy and in particularly cold days the yield of the heat pump results insufficient, since the heat taken from the external environment is minimal and the consumption of the compressor increases because greater effort is needed. Another characteristic of the refrigerant fluids lies in that when they are in their container they tend to be distributed in such a way as to have constant pressure, which can be affected by the external temperature, by the pressure, by the quantity of liquid, and therefore the fluid in the liquid state tends to evaporate until reaching the balance pressure. A further characteristic of these fluids lies in that, if pressurized, they tend to heat up and this takes place to a degree that depends on the type of refrigerant fluid. Example: For one of the most known gases, freon 22, manufacturers indicate the following yields: 10 bars = 27°, 20 bars = 53°, 30 bars = 71°, 40 bars ^« 84°, 50 bars = 96°, 60 bars = 106° etc, to which the heat produced by the operation of the compressor should be added.

Today compressors and pressure multipliers are produced in order to allow the desired pressures to be achieved. Now it is necessary to analyze the consumption involved, for example, in the operation of a system with which we want to heat 1 ,000 litres of water per one hour using the traditional systems, considering that the water reaches the inlet of the heat exchanger at a temperature of 15° and flows out heated to a temperature of 50°. Calories needed:

1 calorie per 1 litre of water per 1 heating degree

50° water outlet temperature

15° water inlet temperature

35° increase to be achieved expressed in degrees 1.000 quantity of water to be heated, expressed in litres

35.000 calories needed

3500 x 1,116 = 39 Kw/h required Gas oil heating:

8.500 calories delivered in 1 hour with 1 litre 35.000 calories needed

4,1 litres/hour consumed

€.1,20 cost of gas oil per litre

€ 4,90 hourly cost

LPG heating: 8.000 calories delivered in 1 hour with 1 liter 35.000 calories needed

4,4 litres/hour consumed

€.0,90 cost of LPG per litre

€ 3,60 hourly cost The object of the present invention is to produce heat, as constantly as possible, with no influence from the external environment and with the lowest possible energy costs.

Heating with refrigerant fluid:

In this solution we shall indicate the energy absorption declared by the manufacturers of compressors under conditions that are not optimal compared to those obtainable from the system that is the subject of the invention.

In the proposed conditions, we calculate a COP > a 8 with a temperature of

58° at the heat exchanger. 39.00 Kw/h needed

8 COP

4.7 ^' Kw/h needed

€. 0,17 cost per Kw/h

€. 0,78 hourly cost. The above description shows that it is possible to achieve considerable savings; furthermore, it is very important to underline that if the invention is applied to heating systems in highly populated cities, it ensures a considerable reduction in atmospheric pollution caused by gas oil or LPG burners. In order to overcome all the drawbacks described above, a new heater with heat pump operating at different pressures has been designed and constructed.

The new heater with heat pump operating at different pressures differs from the other systems in that it uses exclusively the characteristics of refrigerant fluids, or compressible fluids, eliminating the section of the evaporator that changes the fluid to the liquid state but using the refrigerant fluid only in its gas phase.

The characteristics of the new heater with heat pump operating at different pressures will be better illustrated in the following description with reference to the drawings, attached by way of non-limiting example.

The new heater mainly comprises a tank for the refrigerant fluid (B, C), at least one compressor pump (E), at least one heat exchanger (G), at least one pressure reducing valve (H). In the tank (B, C) the refrigerant fluid at rest is present in the two liquid and gas states and a pressure of approximately 7-10 bars is generated depending on the type of refrigerant fluid used, on the quantity of fluid in the liquid state contained therein and on the external temperature. The refrigerant fluid in the liquid state is distributed on the bottom of the tank (B), while the refrigerant fluid in the gas state is distributed in its upper part (C).

The compressor (E) draws the refrigerant fluid in the gas state from the upper part of the tank (C) and conveys it towards the heat exchanger (G). In order to obtain suitable compression of the refrigerant fluid in the heat exchanger (G), on the outlet pipe of the heat exchanger (G) there is a pressure reducing valve (H) that lets the refrigerant fluid flow at the previously defined and set pressure, also according to the temperature to be obtained.

The fluid cooled by the heat exchanger (G), once it has passed beyond the valve (H), is saturated and compressed in an area of low pressure and tends to become liquid again. Said refrigerant fluid in the liquid state is conveyed again towards the inside of the tank (B, C), from where it restarts its cycle. Even if the fluid should not be changed into the liquid state, because the heat exchange and condensation beyond the pressure reducing valve (H) have not made it completely liquid, this doesn't cause any problems, since the fluid is drawn from the tank (B, C) in the gas state.

The new heater with heat pump operating at different pressures makes it possible to produce heat in any climate and with considerable energy savings, since no heat is dispersed towards the outside. The compressor (E) is thus facilitated, since it just has to overpressurize the fluid in the gas phase, given that the tank (B, C) already has its internal pressure.

The pressure reducing valve (H) is preset or it can be set to the desired operating pressure in order to obtain the necessary operating temperature. In a further embodiment of the invention, illustrated in Figure 2, there are one or more liquid pumps (M) that take the fluid in the liquid state from the bottom of the tank (B) in order to convey it to an expansion valve (I) and to one or more evaporators (P), if necessary even to produce cold. The fluid evaporated in said evaporators (P) is conveyed to the compressor (E) through a suitable duct (N). According to the invention, an accumulator tank (A) can be inserted between said expansion valves (I) and said evaporators (P). Also with this solution, with differentiated suction and delivery of the fluid, it is possible to obtain considerable savings in the production of cold, since a liquid pump (M) that absorbs 1.5 KW/h, suited to change refrigerant fluids to the liquid state under the pressures necessary for the correct operation of the system, as shown by the characteristics indicated by the manufacturer, obtains 2.400 1/h with a refrigerant yield of approximately 400 KW. In order to obtain the same result with the traditional compressors at a positive temperature, a power absorption of approximately 200 KW would be required. The system of the new heater with heat pump operating at different pressures can be provided with all the devices, also electronic, suited to allow it to be regulated for the different controls and settings. The valve (H) can also be regulated electronically and automatically, operating based on the set running temperatures or pressures. The system of the new heater with heat pump operating at different pressures can be provided with a duly programmed electric or electronic board that ensures its automatic operation; said electric or electronic board can in turn be provided with an interface suited to allow collection and filing of the obtained data, programming, various setting operations, even remote, and to give malfunction alarms.

The compressor pumps (E) can also be provided with an inverter to regulate consumption and operating power, according to the requirements of the system.

The liquid pumps (M) can be provided with an inverter to maintain a constant delivery pressure. The system of the new heater with heat pump operating at different pressures can be partially or completely sound-proofed in order to make it compatible with the laws in force, according to which it is not allowed to exceed a given number of decibels, especially in residential areas.

Therefore, with reference to the above description and the attached drawings, the following claims are expressed.

Claims

CLAIMS 1. Heater-Cooler, characterized in that it comprises:

- at least one tank (B, C) for a refrigerant fluid,

- at least one compressor (E), - at least one heat exchanger (G),

- at least one pressure reducing valve (H), and wherein the fluid in the gas state inside the tank (C) is drawn by said compressor (E) and conveyed, under pressure, to said heat exchanger (G) and to said pressure reducing valve (H), said fluid being compressed at controlled speed and pressure in the duct that conveys it again to said tank

(B, C), and wherein said fluid, owing to the pressure generated by said compressor (E), raises its temperature and transfers heat through said heat exchanger (G).

2. Heater-Cooler according to claim 1, characterized in that it comprises at least one liquid pump (M) suited to draw the fluid in the liquid state from the bottom of the tank (B) and convey it, through at least one expansion valve (I), towards an evaporator (P) in such a way as to change the fluid to the gas state, and wherein said fluid in the gas state flowing out of said evaporator (P) is conveyed to the inlet of said compressor (E).

3. Heater-Cooler according to the preceding claim, characterized in that it is provided with an auxiliary tank (A) included between the expansion valve (I) and the liquid pump (M).

4. Heater-Cooler according to the preceding claims, characterized in that said pressure reducing valves (H) can be directly or indirectly adjusted in such a way as to modify the flow rate, pressure and speed of the fluid flowing through them.

5. Heater-Cooler according to the preceding claims, characterized in that each pressure reducing valve (H) is provided with an automatic regulator piloted by a pressure and/or temperature indicator that optimize its operation.

6. Heater-Cooler according to the preceding claims, characterized in that said compressors (E) are provided with a frequency inverter regulated by a pressure and/or temperature indicator that optimize its operation.

7. Heater-Cooler according to the preceding claims, characterized in that said liquid pumps (M) are provided with a frequency inverter regulated by a pressure and/or temperature indicator that optimize its operation.

8. Heater-Cooler according to the preceding claims, characterized in that said pumps (M) and said compressors (E) can be connected in parallel and be programmed in such a way as to intervene individually or all together, if necessary alternating in order to work for the same or a different number of hours.

9. Heater-Cooler according to the preceding claims, characterized in that said compressor (E) is cooled according to the operating temperatures and pressures used.

10. Heater-Cooler according to the preceding claims, characterized in that it is equipped with an electric/electronic system connected to a control board for remote control and adjustment, and wherein said control board can be interfaced to a computer for control and programming activities.

11. Heater-Cooler according to the preceding claims, characterized in that it is equipped with all or part of the instruments used in the traditional systems, like filters, valves, temperature indicators, pressure indicators, absorption indicators, antivibration devices, etc.

12. Heater-Cooler according to the preceding claims, characterized i in that it is partially or completely sound-proofed.