EP4729855A1 - Method of utilization of the output heat of the working medium of the condenser - Google Patents

Abstract

The subject of the application is a method of using the output heat of the working medium of a condenser included in an absorption chiller, in which method, after the working medium has reached the output heat, the working medium leaving the condenser is led out and directed to at least one external device, then the working medium passes through the external device, where it gives off the output heat to this external device, and then said working medium is directed back to the condenser.

Description

• The subject of the invention is a method of using output heat of the working medium of a condenser included in an absorption unit in cogeneration systems. The method enables the use of heat of the working medium, which the working medium has absorbed from the refrigerant during its condensation.
• There are known systems that use waste heat generated during the production of electricity to generate heat. These systems, called cogeneration systems, use waste heat in one of two ways: directly, where the heat from the engine block is recovered and used for further heating, and in addition, via an exchanger, the heat of exhaust gases is used - the total waste heat is used by redirecting this heat to any other receiver; or by using waste heat to produce chilled water using an absorption unit, where the heat of chilled water is transferred to the unit's evaporator during the condensation of the refrigerant, which allows its temperature to be lowered.
• An absorption chiller is a device for producing cold (chilled water) through the circulation of a refrigerant that receives the heat of the cooling cycle, and thus to cool the chilled water. In the basic absorption cycle, the generator uses a heat source to evaporate the refrigerant from a diluted solution of lithium bromide, after which the evaporated refrigerant in the form of vapour goes to the condenser, where it is condensed by transferring heat to water (in this document referred to as the working medium or working medium of the condenser), after which, after condensation, the refrigerant in liquid form is directed through the evaporator, thereby cooling the chilled water and evaporating again, and the resulting vapour is directed to the absorber, where it is absorbed by the concentrated absorbent solution. The diluted absorbent solution obtained in this way is then pumped back to the generator. Water is used as the refrigerant, and the absorbent is lithium bromide.
• The heat released by the working medium of the condenser is released to the environment. It is low-parameter, condenser heat. As a rule, it is released to the environment using an open or closed circuit cooling tower, less often using adiabatic Dry Coolers, but it is always irreversibly released to the environment.
• Systems using the above processes are widely used in generating electrical and thermal energy and allow the use of part of the thermal energy generated during fuel combustion, but this is only the part of this energy that is in the high-parameter range. None of the known solutions refer to the full use of the absorption unit's potential and the full use of the heat of the working medium of the condenser - they do not ensure the use of waste heat of the medium used to condense the refrigerant, in other words, at the condenser outlet, the heat of the working medium that absorbed heat from the refrigerant is not used any further. Even in the literature, the condenser cycle is defined as a system from which heat should be released to the environment.
• Known devices from the state of the art do not offer methods for ensuring the use of this output heat of the working medium, because it is low-parameter heat. Known solutions direct the heat of the working medium to cooling towers and distribute the output heat of the working medium to the environment.
• Alternatively, this heat is used in systems supported by additional devices, such as heat pumps. However, there is a lack of solutions that use this waste heat without the need for additional devices requiring additional power.
• The Applicant's solution provides a method of using the output heat of the working medium of the condenser belonging to the absorption unit, which would normally be treated as waste and released into the environment, without the need to install energy-absorbing systems, and thus increases the efficiency of cogeneration systems and the total output power obtained from the system and ensures better use of the energy consumed in those systems. A method of using output heat of the working medium of a condenser included in an absorption unit, wherein the working medium, during condensation of the refrigerant of the absorption unit, absorbs heat from the refrigerant and achieves its output heat at the outlet of the condenser, is characterized in that it comprises the steps of:
• after the working medium reaches the output heat, discharge of the working medium leaving the condenser;
• directing the working medium to at least one external device via appropriate technical means;
• directing the working medium through an external device, where the working medium releases its output heat to the external device;
• directing the working medium back to the condenser.
• Preferably, the external device is at least one of a low-parameter heater, an underfloor heating, a heater of an air-conditioning unit or a ventilation unit, a technological receiver, or a hot water tank.
• Preferably, the relevant technical means are at least one of a pipe and a pipeline.
• Preferably, the working medium, after the step of discharging the working medium from the condenser, may be directed to a cooling tower.
• Preferably, directing of the working medium to at least one external device is dependent on priority and/or reported demand.
• Preferably, the output heat of the working medium has a temperature of 25 to 60 degrees Celsius, preferably 35 to 45 degrees Celsius.
• In order to facilitate understanding of the principle of operation of the invention, the following is a description of an exemplary embodiment and drawings, which are intended to facilitate understanding of the invention and are not intended to limit it, in which:
• Fig. 1 shows an exemplary diagram of an absorption unit known from the state of the art, where the output heat of the working medium is indicated;
• Fig. 2 shows a system in which heat is released according to the method of the invention;
• Fig. 3 shows a comparison of the power obtained from a classical cogeneration system and the power obtained from a cogeneration system using the method according to the invention.
• As shown in Fig. 1, in the solutions known from the state of the art, the working medium, for example water, passes through the condenser of the absorption unit, receiving heat therein from the refrigerant of the unit, i.e. water in the form of steam, which causes the condensation of the refrigerant and the temperature of the working medium to increase to 36-45 degrees Celsius. This medium is then removed from the condenser, and the heat is released to the environment.
• Fig. 2 generally shows an exemplary system implementing the method according to the invention. The system comprises an absorption unit, transmission technical means, circulation pumps and at least one external device. The absorption unit, or more precisely the output means of the working medium cooling the condenser included in this unit, are connected to the aforementioned external devices via transmission technical means. Additionally, the appropriate flow of the working medium to the external devices is carried out using circulation pumps. The transmission technical means are pipes, and in another embodiment it is a pipeline. In the absorption unit, the working medium of the condenser, during the condensation of the refrigerant of the absorption unit, absorbs heat from the refrigerant and reaches its output heat at the outlet of the condenser. In the method according to the invention, the step of discharging the working medium leaving the condenser and the step of directing the working medium to at least one external device via the aforementioned appropriate technical means take place, after the working medium reaches the output heat. Next, the working medium is conducted through the external device (external devices). In this step, the working medium gives off the output heat to the external device. The last step of the present method is to direct, by means of appropriate technical means, the working medium back to the condenser.
• In various embodiments, the external device is: a low-parameter radiator, underfloor heating, an air conditioning or ventilation unit heater, a technological receiver, or a hot water tank, wherein in the system of Fig. 2 it is possible to use only one external device, but embodiments with any combination of a larger number of external devices are also possible.
• The step of heat transfer to the external device depends to some extent on the type of external device, for example:
• when heating domestic hot water tanks, the heat released from the working medium can be the target heat source, increasing the temperature of the domestic hot water when the target water temperature is not high or alternatively, when a high target water temperature is required, the heat from the working medium can provide an initial temperature increase for subsequent heating - this ensures energy savings because the amount of energy required for subsequent heating is lower;
• when heating the medium operating in low-parameter radiators, in air conditioning and ventilation or in underfloor heating - analogously to the example concerning hot water tanks, heat is released by releasing the heat of the working medium to the medium operating in these radiators, air conditioning and ventilation or underfloor heating.
• It should be noted that the heat from the working medium is released by means of heat exchange between the working medium and the medium of the external device - there is no use of the working medium from the condenser of the unit in external devices.
• In one embodiment, when a failure occurs in a system with external devices or there is no demand for heat in any of the external devices, after the step of removing the working medium from the condenser, it is directed to a cooling tower.
• In an alternative embodiment, the system, for example the system of Fig. 2, includes a controller that enables the working medium to be directed to at least one external device. In one embodiment this step of directing the working medium is dependent on priority, and in another embodiment it is dependent on a reported demand.
• The output heat of the working medium used in the subject method has a temperature in the range of 25 to 60 degrees Celsius - typically it is the range of 35 to 45 degrees Celsius, i.e. the low-parameter temperature range used by the external devices mentioned above.
• As shown in Fig. 3, using the method according to the invention, it is possible to utilize all waste heat, which significantly increases the efficiency of the system and increases the amount of obtained useful power in comparison with the classic cogeneration system. The Applicant conducted a comparison of the classic cogeneration system and the cogeneration system implementing the method according to the invention and obtained a significant energy gain in comparison with the classic system. The results of the comparison are presented in Table 1. Table 1

  Devices used in tests
  Engine with Generator: MTU 20V4000GS (GG20V4000A1)
  Total output heat	1441kW
  Exhaust gas heat	1290kW
  Electrical power	2538kW
  Input power	5955kW

  Absorption Unit: 16LJ-F63
  Cooling capacity	2074kW
  Thermal power input	2701kW
  Thermal power output	4769kW

  RESULTS
  Classic system in heat recovery mode
  Input power	5955kW
  Electrical power	2538kW
  Heat capacity	2701kW
  Efficiency	88%
  $${\epsilon }_{\mathit{ff}}=\frac{{\displaystyle \sum E_{\mathit{in}}}}{{\displaystyle \sum E_{\mathit{out}}}}$$

  Classic system in cooling mode
  Input power	5955kW
  Electrical power	2538kW
  Cooling capacity	2074kW
  Electrical power	77% (without taking into account the power required to release the condenser heat (approx. 75kW) and the lost water (approx. 2.51/s) - taking into account the efficiency is approx. 75%)
  $${\epsilon }_{\mathit{ff}}=\frac{{\displaystyle \sum E_{\mathit{in}}}}{{\displaystyle \sum E_{\mathit{out}}}}$$

  A system using the method according to the invention
  Input power	5955kW
  Electrical power	2538kW
  Cooling capacity	2074kW
  Heating capacity	4769kW
  Efficiency	157%
  $${\epsilon }_{\mathit{ff}}=\frac{{\displaystyle \sum E_{\mathit{in}}}}{{\displaystyle \sum E_{\mathit{out}}}}$$

• The examples given herein are merely non-limiting indications of the invention and cannot in any way limit the scope of protection, which is defined by the patent claims. It should be understood that the method according to the invention is not limited to the use on the above-described devices and systems and may be implemented on equivalent systems or by means of equivalent technologies without thereby departing from the scope of protection.

Claims (6)

1. A method of using output heat of the working medium of a condenser included in an absorption unit, wherein the working medium, during condensation of the refrigerant of the absorption unit, absorbs heat from the refrigerant and achieves its output heat at the outlet of the condenser, characterized in that it comprises the steps of:

   - after the working medium reaches the output heat, discharge of the working medium leaving the condenser;

   - directing the working medium to at least one external device via appropriate technical means;

   - directing the working medium through an external device, where the working medium releases its output heat to the external device;

   - directing the working medium back to the condenser.
2. The method of using the output heat of the working medium according to claim 1, wherein the external device is at least one of a low-parameter heater, underfloor heating, a heater of an air-conditioning unit or a ventilation unit, a technological receiver, a hot water tank.
3. The method according to any one of the preceding claims, wherein the respective technical means are at least one of a pipe and a pipeline.
4. The method according to claim 1, wherein the working medium after the step of discharging the working medium from the condenser may be directed to a cooling tower.
5. The method according to claim 1, wherein directing the working medium to the at least one external device is dependent on priority and/or reported demand.
6. The method according to any one of the preceding claims, wherein the output heat of the working medium has a temperature of 25 to 60 degrees Celsius, and preferably 35 to 45 degrees Celsius.