Countercurrent layer heat exchanger
The countercurrent layer heat exchanger (GSWT) is a recuperative heat exchanger that is made up of vertical heat exchanger layers .
With the GSWT thermal energy is transferred between a gaseous medium - e.g. B. air - and a liquid medium - z. B. water glycol mixture - transferred. This pairing of the media leads to the design of a lamellar heat exchanger in which the liquid is guided in cross- countercurrent (99% countercurrent behavior).
In this design, powerful and efficient heat exchangers are implemented, which also combine full cleanability and redundancy . The standard design is designed for a temperature exchange rate of 90% with the same heat capacity flows. A hydraulic connection between two countercurrent layer heat exchangers results in heat recovery . The heat recovery created in this way is then absolutely free of germs and pollutants and, even in the event of a malfunction, without any smoke or fire transmission.
Distinguishing features
The GSWT consists of horizontally separable heat exchanger layers that are separated by dividing lines. As a result, active cleaning flow channels are formed. The GSWT can be completely cleaned down to the core, both in the assembled and in the dismantled state. The dismantling is useful for transport, assembly, disassembly and cleaning. The increased redundancy is explained by the fact that each individual layer is functional, lockable, drainable and gas-sealed. If one shift fails, the remaining shifts will continue to function until the next maintenance date.
Efficiency
The efficiency here characterizes the profitability of the heat transfer process. As much benefit (heat output) as possible should be achieved with little effort (pump and fan energy). A key figure for efficiency is the ratio of the heat output to the delivery rate of the pump and fan. In the case of heat transfer processes, this figure is also related to a useful temperature lift of 1 ° C. With the GSWT, this related efficiency is always higher than 4: 1 with the same heat capacity flows. For example, if the air temperature is to be increased by 30 ° C, the efficiency is 30 * (4: 1) = 120: 1. This means that only one part of the conveying capacity is required to provide 120 parts of thermal output.
chronology
In 1973, the year of the first energy crisis, the first heating and cooling registers were combined to form simple heat recovery systems. During the second energy crisis (1979), their performance was no longer sufficient and the development of the highly efficient GSWT began, so that in 1983 it was ready for the market. The first two GSWTs used work in a heat recovery system (WRG) that is interconnected via a circuit system (KV system ). Three years later, the GSWT was a component with which multifunctional use could be implemented.
Cleanability
Soiling or deposits can cause considerable problems with heat exchangers. There are essentially two problem cases:
- Impairment of function (pressure loss, thermal resistance)
- Hygienic impairment (contamination e.g. with bacteria, viruses, fungi)
With the GSWT, three mechanisms of action take effect when cleaning when installed. These are:
- Pressure energy . This avoids deposits and clogging, which usually impair the function. On the air side, the GSWT consists of many fine flow channels that are very smooth on the inside and have no transverse profiles or joints. The flow channels ensure that the full pressure difference between the air inlet and outlet always loosens any blockages and thus causes self-cleaning effects.
- Conservation of momentum . With manual cleaning, the flow channels ensure that a cleaning jet cannot spatially spread. As a result, it does not lose speed or cleaning power over the entire course through the heat exchanger.
- Surface wetting . A cleaning jet floods the flow channel to be cleaned over its entire length. This means that every point is permanently washed around. Cleaning agents, which have to completely and permanently wet the entire surface in order to achieve the best effect, can be used without mechanical action by dissolving, disinfecting or chemical. Conversion Remove dirt or germs.
Only the simplest cleaning methods are used for cleaning down to the core: suction, blowing or rinsing. High-pressure cleaning, which can easily ruin slats or coatings, is not necessary and would only make sense for the dismantled state. Every single layer of the dismountable GSWT is then viewed and cleaned from all sides down to the deepest core. The cleaning result can be checked visually or with recognized test methods immediately and at any point, as the entire surface is accessible when dismantled - also because of the low height between the slats.
Heat recovery and multifunctional use
The aim of multifunctional use is to cover as many technical functions as possible with as few structural units as possible. Systems of this type are very compact in terms of dimensions and offer increased economic benefits due to their efficiency. They are mainly used for heat recovery (WRG) in air conditioning systems. As a basic unit, two GSWT are interconnected via a circuit system (KV system) for heat recovery. Additional functions for multifunctional use can be connected to this base unit as accessories:
- Indirect adiabatic evaporative cooling creates a cold potential by humidifying an air flow that is to be removed anyway. This cold potential is transferred with the basic system to the supply air flow to be cooled. In most cases, this saves mechanical cooling.
- Integrated air and heat exchanger circuit for night- time cooling enables night-time cooling and night-time cooling to be carried out at the same time.
- Use of naturally occurring cold potentials such as well water, geothermal cold etc.
- Integrated solar heat utilization via the KV system uses solar -generated heat from 20 ° C for heating purposes.
- Integrated reheating via the KV system saves the heating register
- Integrated after-cooling via the KV system saves the cooling register
- Integrated mechanical refrigeration integrates mechanical refrigeration and integrates the evaporator side into the KV system. This saves the cooling register and cooling centers.
- Integrated dehumidification cooling still achieves the required cooling capacity with the highest possible cooling temperature when the dew point is not reached. This greatly increases the COP value of the mechanical refrigeration machine required.
- Integrated dehumidification cooling recovery enables simultaneous reheating and cooling recovery without the use of primary energy.
- Room air coolers can be supplied with outside air cooling via the KV system.
- Integrated free cooling feeds cold into the buffer tank via the KV system, daytime heat and post-cooling can then be drawn off at peak loads.
- Integrated refrigeration machine recooling integrates mechanical cold generation and integrates the condenser side into the KV system. This saves the recooling plant.
- Integrated combined heat and power unit (CHP) uses electricity and heat on site. No additional cooler is required to cover electricity peaks in summer.
Areas of application
Typical areas of application are
- Air conditioning systems (hospitals, office buildings, swimming pools, businesses, airports, automotive industry)
- production engineering systems
- process plants
- Power plants
to call.
use
See also
literature
- H. Schnell: Heat exchangers, energy saving through optimization of heating processes. , 2nd edition., Vulkan-Verlag Essen 1994, ISBN 3-8027-2369-4
- Herbert Jüttemann: Heat and cold recovery. , 4th edition. Werner Verlag Düsseldorf 1999, ISBN 3-8041-2229-9
- Recknagel-Sprenger-Schramek: Pocket book for heating + air conditioning. , 73rd edition. Oldenbourg Industrieverlag Munich 2007, ISBN 3-8356-3104-7
- VDI Society for Technical Building Equipment: VDI guideline VDI 6022 , hygiene requirements for ventilation and air conditioning systems and devices, Beuth-Verlag 2006