Pre-cooling systems

For pre-cooling system Coolerado Company has RF100. This unit is engineered to connect Coolerado M50’s cooler to the existing rooftop unit. It has two modes: free-cooling mode and pre-cooling mode. When the weather conditions are favorable it works in free-cooling mode and supplies fresh air to the building. It handles the entire cooling load of the building. The existing rooftop unit is bypassed.

When the humidity of the ambient air is high RF100 works in pre-cooling mode. It reduces the cooling load on the main air conditioning system. This solution helps to reduce energy consumption of the air conditioning system. RF100 unit is shown in the Figure 17. /15./

FIGURE 17. RF100 pre-cooling system /15/

Stand alone systems

For stand alone coolers at this moment Coolerado has three units. They are M30, M50 and C60 (Figure 18). All of them have a modular design. That means that they could be stacked side by side with each other to increase the total cooling power.

FIGURE 18. Coolerado cooling units M30, M50, C60 /15/

These three units which differ by the maximum air flow rate and thus by power. Characteristics of those units are shown in the Table 1.

TABLE 1. Technical information of M30, M50 and C60 units /15/

Those units are not very different from each other. They differ mainly in flow rates and therefore in cooling capacity. But the wet bulb temperature approach is almost the same. Energy efficiency ratio is very high. For comparison, an EER class A corresponds to the value more than 3.2, but in case of Coolerado coolers it could reach values more than 40. /16, p.9/.

Hybrid systems

For special cases Coolerado Company has hybrid system H80. It has two stage compressor with R-410A refrigerant system. This air handling unit offers the possibility to heat the air flow. It is also high-efficient solution for the locations, where the Coolerado air conditioner cannot take the full cooling load. The maximum cooling capacity of this unit is 17,6 kW and the maximum heating capacity of the refrigeration circuit is 44 kW. The flow rate of the supply air in the H80 is about 940 l/s. The scheme of the H80 unit is shown in the Figure 19. /15./

FIGURE 19. Coolerado H80 hybrid system /15/

The outside fresh air comes through the outside damper (1). For instance its temperature is 43 °C. Then it goes to the filters (2) and enters the HMX (3), where it is divided in to two flows. The product air, which is cooled by the working air, leaves the HMX with the temperature about 22 °C and with no change in humidity (4). After that the air stream enters the refrigerant coils (5) and with the fan is distributed to the rooms (6). The temperature of the distribution air is about 13 °C which is approximately 30 °C less than the outside air. The working air takes heat from heat exchangers and is exhausted to the outside (7,8). The temperature of the saturated air after the HMX will be about 26 °C and after hot coils about 36 °C. /15./

If there was only traditional cooling system with compressor, than the temperature of condenser should have been more than 43 °C and the temperature of evaporator less than 13 °C. That means temperature difference between evaporation and condensation temperatures more than 30 °C. On the other hand in hybrid system the air flow at first goes through the HMX and comes to the condenser with the temperature about 26 °C and to the evaporator about 22 °C. That means much less temperature difference between condensation and evaporation in comparison with stand-alone compressor system. Higher temperature difference means more work for the compressor and therefore less COP and higher energy consumption. So that the HMX in the hybrid system makes the work of compressor cooling system more efficient.

Date: 2015-12-11; view: 2627