M1M3 Fan Coil Unit Status Gary Muller & Brian Johnson LSST 2017 Project & Community Workshop 8/17/2017

Fan Coil Unit (FCU) Overview There are 96 FCUs inside M1M3 Mirror Cell that circulate conditioned air through the mirror cores via >1650 vent tubes

FCU Location IDs in M1M3 Cell F1, F2, F3, …, F96 Installation drawings: 13-00055 Direct FCU Installation 13-00185 Offset FCU Installation

Inlets Mount To Deck Plate For direct ducts For offset ducts Captive screws No flange for flexible duct Flange for attaching rigid duct Marmon clamp

FCU Configurations Offset duct Long duct Short duct No duct Offset ducts are non-structural. FCU must be supported by a bracket attached to structure. Direct ducts are structural and provide cantilever support of FCUs. Offset FCU Direct FCUs

Diffuser cone inlet with 40 w and 60 w blanket heaters FCU Detail Diffuser cone inlet with 40 w and 60 w blanket heaters Heat exchanger EGW coolant Nozzle cone Thermo-couples Centrifugal fan Inner loop Controller

Distribution of FCUs in M1M3 Cell Placement of FCUs is limited by mirror support system components. Actuators, hard points, mirror cell structure

EGW Coolant Loops Supply loop Return loop Recirculation pump assy

1650 Mirror Core Vent Nozzles

Mirror Core Vent Nozzles

Current Status 110 FCUs have been assembled, leak tested, and await acceptance testing Conducted inlet fit check with M1M3 cell deck plate at CAID in July EGW supply/return hoses have been procured and received Marmon clamps and rigid ducts have been procured and received Offset FCU mounting brackets have been fabricated and received Need to procure flexible ducts (11X) for Offset FCUs

Completed FCU

110 Completed FCUs Ready for Test & Integration

Acceptance testing (Test plan is under construction) Future Plans Acceptance testing (Test plan is under construction) Fan speed / air flow rate Vary air flow rate Heater power Vary heater power 50°C thermostat cutoff switch Vibration measurements EGW flow rate / temperature Need to decide whether to conduct this test Will need EGW chiller system to test (currently none)

Procure flexible ducts for offset FCUs Procure shipping crates Future Plans Drill and tap mounting holes in M1M3 cell for offset FCU mounting brackets (11x) Procure flexible ducts for offset FCUs Procure shipping crates Integration into M1M3 cell Install inlets Install ducts and FCUs Wire routing and electrical boxes

Supplemental Slides

Principle of Operation Air is drawn from the mirror cores into 96 6” diameter inlets in the deck plate by low pressure in the FCU The air passes downward through a diffuser after the inlet where blanket heaters on two diffuser cones heat the air as needed. Temperature sensors on the mirror measure absolute temperature and thermocouples on the FCU measure the temperature change through the FCU for the thermal control feedback loop. The air then continues downward through a heat exchanger and is cooled via chilled ethylene glycol / water mixture A centrifugal fan draws the conditioned air from the heat exchanger and is ejected radially outward into the enclosed volume of the M1M3 mirror cell. The conditioned air is then forced into >1700 nozzles upward into the mirror cores where they heat or cool the mirror thus, completing the cycle

No Duct Inlet Marmon Clamp Fan coil unit

Short Duct

Long Duct Inlet Marmon Clamp Long duct (rigid) Fan coil unit

Offset Duct Inlet Marmon clamp Flexible duct Mounting Bracket Hose clamp Fan coil unit

Original Diffuser Design Flow Stagnation

1st Iteration of Diffuser Design Eliminated stagnated flow but flow is concentrated at center Changed diffuser geometry and changed nozzle after heat exchanger

2nd Iteration of Diffuser Design (Final Design) Flow distributed over larger area of heat exchanger for maximum heat transfer Added two diffuser cones