Galletti LCE 244 HQ Инструкция по эксплуатации онлайн [28/64] 463243

LCE

RG66004766_rev.05

Free-cooling execution provides excellent energy savings in all those situations in which the outside

temperature is lower than the fluid in circulation (process industry, close control applications, information

technology in general, convention halls, etc.). The performance of the free-cooling circuit depends on the

difference between the outside air T and that of the water circulating, as shown in the figure (fig. 6).

when the T2 of the outside air falls below the T2 of the T1 of the water returning from the system, this will

generate a thermal exchange and the free-cooling action begins with integration of one or more

mechanical cooling steps. At this stage it is essential to have the maximum air flow rate in order to

maximise the performance of the free-cooling coils and, at the same time, effectively control the

condensation pressure. Condensing coils are fitted with a special partialization circuit that reduces the

surface of thermal exchange and therefore allowing the unit to operated with the full air flow rate (fig.7).

Indeed both sections of the coils are usually operative in the mechanical-only cooling mode, but when the

Free-Cooling mode - therefore with T2 of the outside air below (T1-Delta T)°C - in the event of a

simultaneous mechanical cooling request (integration), section 1 is excluded and ventilation runs at full

speed whilst maintaining excellent control of the condensation pressure.

With total free-cooling, the chilling yield is modulated by adjusting the speed of the fans to keep the outlet

T of the water constant.

To prevent any blockages of the 3-way valve, this is automatically switched up to 30% once every 140 h

of operation whilst the chiller keeps running.

Chilling

ield

T outside air

Return

water T

Free Cooling

ield

Chiller yield

Simultaneous

operation

Free Cooling

only

Nominal yield of

the chiller

FFT Full Free Cooling

temperature

. 6

Section 1

Section 2

fig. 7