**4.2.13 Target Pile Air Cooling System**

The purpose of the air cooling system is (1) to keep the pit floor and
walls at approximately 12.8 °C, (2) to remove the following heat loads:
beam heating - 158 kW, stripline - 2.4 kW, ambient - 3.4 kW, fan - 50
kW, (3) to dehumidify at a rate of 20 kilograms/hour at the 158 kW beam
heating load, and (4) filter particulates from the airflow. The
automatically controlled system is designed to provide 240 kW of
cooling, and to circulate and filter 750 Nm^3^ of air per hour. The high
efficiency particulate filters have a minimum removal efficiency of
99.97% with 0.3-micron size particles. The dehumidification rate is
based on a leak exchange rate between the target hall and the target
pile of 2.5% of the design airflow rate. The filters are installed in
bag-in/bag-out housings.

The flow schematic is shown in **Figure 4.2-1 a & b**. It is discussed
below, starting where the cooling airflow exits the target pile.

Temperature and humidity of the air exiting the target pile are
monitored. Humidity of the target hall is also monitored.

Pressure drop across the particulate and high efficiency filter banks
are individually monitored. High differential pressure across either
bank will shutdown the fan. It is very important to change the filters
at the specified pressure drops. In particular, the prefilter will come
apart at high-pressure drops, and unload the particulates trapped in it.
This will unnecessarily load the much more expensive high efficiency
filters, most likely requiring that they be changed immediately.

The airflow is cooled after filtering. An automatically controlled air
damper is installed in parallel with the evaporator coils. It will make
moderate adjustments in the amount of air flowing to the evaporators to
reduce the reheat duty. Air damper position can also be positioned
manually. An electrically operated solenoid valve starts or stops the
flow of high-pressure liquid refrigerant 22 to each evaporator coil
based on the system heat load. Solenoid valve operation can be either
automatic or manual. The full-open and full-closed state of each
solenoid valve is monitored using limit switches. A self-operated,
thermal expansion valve automatically controls flow of refrigerant 22 to
each evaporator coil. Evaporator coil header pressure is used to
automatically adjust condenser unit capacity to match the system heat
load. Operating status of the condensing unit is monitored.

The single-speed fan boosts the airflow to operating pressure after
cooling. Fan differential pressure is monitored. The particle beam will
shutdown if fan differential pressure is too low. Fan inlet and outlet
temperatures are monitored. The fan can be started and stopped in either
the target hall or the power supply room.

The reheater heats the airflow to operating temperature when needed.
Reheater operation can be either automatic or manual. The heating
element is equipped with a high temperature switch to protect it from
burning out. Temperature and humidity of the air entering the target
pile are monitored. The particle beam will shutdown if supply air
temperature to the target pile is high or low for too long.

Slow start, smart motor contactors energize the fan and refrigeration
compressor motors. Each contactor will protect its motor from being
damaged by current and voltage irregularities. Each motor winding has an
internal high temperature switch that is included in the control logic
to further protect the motor from damage.

A PLC, programmable logic controller, is used to automatically control
the solenoid valves that start and stop high-pressure refrigerant flow
to each evaporator coil. Control logic for the fan is hardwired. All
monitoring instruments are wired to PLC input modules. The PLC transmits
all monitored signals to Acnet via Ethernet. The signals will be
displayed on Actnet parameter pages. Selected signals are included on
alarm pages and on graphic displays.

The instrument list is given in **Table 4.2-16.5a** and **Table
4.2-16.5b .**

![](media/image1.png){width="5.011805555555555in"
height="8.105555555555556in"}

Table 4.2-16.5a Air-cooling system instrument list -- Part 1

![](media/image2.png){width="5.15in" height="7.998611111111111in"}

**Table 4.2-16.5b** Air-cooling system instrument list -- Part 2

![](media/image3.jpeg){width="6.489583333333333in"
height="8.625in"}**Figure 4.2-****41a:** Air-cooling system flow
schematic

**Figure 4.2-b:** Legend for Air-cooling system flow
schematic![](media/image4.jpeg){width="3.09375in"
height="5.458333333333333in"}