The DK suction gas heat exchanger is for more safety of the compressor and optimizes the compressor and the performance of the cooling unit regarding liquid sub cooling and overheating the suction gas.
- With suction gas liquid heat exchanger the cooling unit could reach till 10% more performance depending of the range of operating
- Better utilization of evaporator through smaller overheating The result is an improvement of performance-quotient Qo/Pe.
- The cooling-power increases and the electric-power is nearly constant
- The safety for compressor is optimal:
- The grease of oil improves through higher suction gas temperature
- The compressor is protected against liquid
- DK suction gas heat exchanger also suitable for refrigerant propane
- It is known that a performance gain can be achieved with liquid subcooling. However, when this is done with a suction gas heat exchanger in the same refrigeration circuit, liquid subcooling results in suction gas superheating.
- In the case of refrigerant R449A, for example, the capacity gain due to liquid subcooling is greater than the capacity loss due to suction gas superheating, which is caused by a larger volume. With a liquid subcooling of 10 K in a refrigeration system with t0 -10°C, there is a capacity gain of approx. 10%. For other refrigerants – for example R134a – a lower capacity gain must be assumed. However, it is very important that the increase in discharge gas temperature is taken into account.
Accordion 1
One topic has been causing an uproar in the refrigeration industry in recent years – the F-Gases Regulation II of the European Parliament. The available quantity of refrigerants containing partly fluorinated hydrocarbons (HFC) is limited and gradually reduced, so the industry needs an alternative for R404A and R134a, among other things. One possible choice is the natural refrigerant propane, and it is known that a performance gain can be achieved with liquid subcooling. However, if this is done with a suction gas heat exchanger in the same refrigeration circuit, liquid subcooling will result in suction gas superheating. In propane systems, a suction gas superheat of about 20°C is required at the compressor inlet. This superheating cannot be guaranteed in every system. Therefore, the installation of a DK suction gas heat exchanger is recommended.
These DK suction gas heat exchangers, which have been produced by DK since 2002, ensure optimum compressor safety. Due to higher suction gas temperatures, the oil in the compressor remains more lubricated, which is an advantage for the compressor. In addition, the complete evaporation of any liquid particles prevents liquid hammering. An exact calculation of liquid subcooling and suction gas superheat is important for every DK suction gas heat exchanger. The DK technicians will be pleased to calculate this for you individually for each heat exchanger or you can use our “heatcool 5.2” design program. A further advantage of the DK suction gas heat exchanger is that the precisely calculated number of inner tubes in the casing tube ensures a balanced ratio of free space for the suction gas and liquid side. This and special supports for the inner tubes are the reasons for operating the DK suction gas heat exchanger without significant pressure losses on both the suction steam and liquid side. DK suction gas heat exchangers with suction line connections from 28 to 133 mm and liquid connections from 16 to 64 mm are supplied with a complete range.
Accordion 2
Functionality:
It is known that a gain in performance can be achieved with liquid subcooling. However, if this is carried out with a suction gas heat exchanger in the same refrigeration circuit, liquid subcooling results in suction gas superheating, which results in a larger specific volume and a reduced mass flow and thus a reduced performance. But: With the refrigerants R404A and R507 the performance gain due to liquid subcooling is greater than the performance loss due to suction gas superheating.
Due to theF-Gases Regulation II, these refrigerants will no longer play the decisive role as in the past. Therefore the question arises:
Can we achieve the significant performance gains in refrigeration systems with R449A?
You can quickly see that we can answer YES to the question asked. With lower power consumption an improvement in the performance of the evaporator is achieved.
However, it is very important that the final compression temperature is taken into account. At temperatures of 120°C and higher, higher capacity gains are achieved, but these are counterproductive due to oil problems in the compressor. This in turn leads to damage to the compressor.
Therefore, a precise calculation of liquid subcooling and suction gas superheat is important for every DK suction gas heat exchanger. At DK this is either calculated by our technicians for each heat exchanger or you can use our “heatcool 5.1” design program for this purpose.
A further advantage of the DK suction gas heat exchanger is that the precisely calculated number of inner tubes in the shell tube ensures a balanced ratio of free space for the suction gas and liquid side. This and special supports for the inner tubes are the reasons for operating the DK suction gas heat exchanger without significant pressure losses on both the gas and liquid side. DK suction gas heat exchangers are available with suction line connections from 28 to 133 mm and liquid connections from 16 to 64 mm.
