NOvA APD Drier System Proposed Design Erik Voirin Fermilab – PPD Fluid and Thermal Engineering Jan 31, 2012 Erik VoirinNOvA APD Drier System1

Specification of Drier System (Mat and Leon) Dew point in APD enclosure: – below -25 o C APD Water Permeation: – 3.5 micrograms per day (NOvA doc-5550) APD Leak tolerance: – 10 inHg/hour when the test volume is evacuated to -25 inHG gauge pressure. Erik VoirinNOvA APD Drier System2

Water Condensation / Frosting Happen when surface temperature is lower than the saturation temperature corresponding to the partial pressure of water vapor in the environment Erik VoirinNOvA APD Drier System3

Water Condensation / Frosting Happen when surface temperature is lower than the saturation temperature corresponding to the partial pressure of water vapor in the environment Erik VoirinNOvA APD Drier System4

Proposed Design Layout Erik VoirinNOvA APD Drier System5

Proposed Design Components Threaded fitting on back of APD spacer – thread to 1/8”ID tube Viton Tube – 1/8” ID x ¼” OD Erik VoirinNOvA APD Drier System6

System Analysis Water Permeates through non-metallic parts – As “dry” air flows through tubing it accumulates water. Water also permeates into APD enclosures – 3.5 micrograms per day – Multiply by 10 for safety margin Ambient Conditions: – 90% Relative humidity – Building required to be below 50% RH Erik VoirinNOvA APD Drier System7

System Materials and Permeation Barb to thread adapters – Polypropylene Tubing – Viton – HDPE (Main Header) Erik VoirinNOvA APD Drier System8

Permeation Coefficients Use properties of water as an ideal gas and Fick’s law to calculate diffusion coefficients and mass permeation coefficients. Diffusion Coefficients Permeation Coefficients Mass Flux Erik VoirinNOvA APD Drier System9

Mass Flux through Viton O-rings Seat poorly (crush only 12%) – O-rings will be crushed more than this, lowering permeation rates Erik VoirinNOvA APD Drier System10

Mass Flux through Tubing Dimensions: 0.25” OD x 0.125” ID Erik VoirinNOvA APD Drier System11

Mass Flow through Threaded Tees Erik VoirinNOvA APD Drier System12

Concentration Difference to APD Previously wrote document on calculating diffusion coefficients of water and oxygen in argon using kinetic theory methods. – bin/ShowDocument?docid=3862 Erik VoirinNOvA APD Drier System13

Previous Diffusion Work – Argon Purge Test of Purification From Atmosphere – MicroBooNe Argon Purge – Erik VoirinNOvA APD Drier System14

Diffusion of Water from APD to Manifold Water Concentration Difference from APD to Manifold with: – APD Flux of 35ug/day 10ug/day into bottom O-ring 25ug into upper enclosure – Diffusion coefficient 0.148cm 2 /sec Erik VoirinNOvA APD Drier System15

Pressure Drop Calculations Erik VoirinNOvA APD Drier System16 Hand Calculations are meant for fully developed flow, which we won’t have Performed Computational Fluid Dynamics (CFD) models using periodic boundary conditions.

Pressure Drop Calculations Erik VoirinNOvA APD Drier System17

Parametric Program to solve each node Calculate – Absolute pressure – Flow rate – Diffusion coefficients – Water content – Permeation flux – Dew point Parameters – Drier Pressure – Initial Flow rate – Permeation Rates – Ambient Conditions – APD Flux Erik VoirinNOvA APD Drier System18

Dew Point Throughout Route 35 micrograms/day APD water permeation Erik VoirinNOvA APD Drier System19

Water Concentration Throughout Route 35 micrograms/day APD water permeation Erik VoirinNOvA APD Drier System20

Dew Point Throughout Route 150 micrograms/day APD water permeation – System Limit (40 times higher than spec) Rate Equivalent to: – 5in 2 of 0.070” thick Viton & 90%RH) – 18 poorly seated O-rings & 90%RH) Erik VoirinNOvA APD Drier System21

Water Concentration Throughout Route 3.5 micrograms/day APD water permeation Erik VoirinNOvA APD Drier System22

System Monitoring (Flow Rate) Erik VoirinNOvA APD Drier System23 Questions??