Cooling Module General Information

Description

The Cooling Module is a re-circulating water chiller. It transfers heat from the liquid coolant that is used to cool the Reagent and Sample Bays. The Cooling Module has a liquid pump that pumps the coolant in a closed loop through the bays and back through the Cooling Module. The Cooling Module uses DI Water as Coolant.

Interfacing Modules

The Cooling Module is connected to the Reagent and Sample Bays via flexible tubing. They are connected in series – Cooling Module > Reagent Bay > Sample Bay and back to the Cooling Module. Each flexible tubing assembly has quick-connect fittings that connect to each of the modules in the cooling loop. The exception is the Cooling Module pump, which is connected by luer fittings.

Theory/Sequence of Operation

The Cooling Module provides chilled liquid coolant to the Reagent and Sample Bays. The Coolant used is DI Water. The module consists of a reservoir where coolant is chilled, eight Peltier heat pumps, a fan for cooling the heat pumps, a liquid pump, and a control board (Cooling Module PCB).

Coolant enters the module reservoir at the inlet quick connect fitting located at the top of the reservoir. The reservoir is a rectangular extruded aluminum tube sealed on the bottom with a removable cap on top.

A sight tube is mounted to one side (front) of the reservoir that allows the fluid level in the reservoir to be observed.

The outlet of the reservoir, located adjacent to the inlet at the top of the module, is another quick connect fitting. Structural foam is mounted to the top, front, rear, and base of the reservoir.

Four Peltier thermoelectric heat pumps are mounted to each of the sides adjacent to the sight tube for a total of eight Peltiers. When a voltage is applied to these Peltier one side gets hot while the other gets cold allowing the device to transfer heat. The cold side of the Peltiers is attached to the wall of the reservoir. The hot side of each Peltier is attached to a finned heat sink. Foam insulation is between the heat sink and the reservoir. A sheet metal shroud (single-fan only) surrounds three sides of the module providing a ducted air path across the heat sinks attached to the Peltiers.Fans are mounted to the shroud on the side of the module opposite the sight tube. The fan(s) forces air through the shroud, across the heat sinks, and out of the system at the right rear corner of the system.

The Cooling Module PCB and liquid pump are located on top of the module and are attached to a sheet metal bracket mounted to the top of the module. The cooling pump is a diaphragm pump with a brushless DC (BLDC) motor that circulates the coolant from the reservoir through the Reagent and Sample Bays then back to the reservoir. The inlet of the pump is connected to the outlet fitting of the reservoir via a flexible tube. The outlet of the pump is connected to a flexible tube that is routed to the inlet of the Reagent Bay. The Cooling Module PCB provides power to the Peltiers, cooling fan, and coolant pump and controls the temperature of the coolant in the reservoir based on the temperature of the Reagent Bay. The Cooling Module PCB also controls the Vacuum Pumps.