Discovery Channel Telescope: Cold Plate Design

At night the ambient air is cooler than the mirror temperature.  When the mirror temperature is higher than that of the ambient air, convective plumes occur which distort the image when looking through the telescope. In order to prevent these convective plumes from occurring, a cooling system must be utilized to track the mirror temperature to ambient.  Engineers at Lowell decided on using a non-contacting cold plate design that uses radiation as its primary mode of heat transfer. Their design concept had a pipe system running underneath a thin face sheet to extract heat given off by M1.  This cold plate as a unit functions similar to a heat sink. When the coolant runs through the cold plate it absorbs some of the heat from the mirror.  Our goal is create an even temperature distribution over the cold plate’s surface otherwise known as the face sheet.   It is necessary to obtain an even temperature distribution so that the mirror does not cool unevenly which would also distort the image.

Below is a 3D model of the overall cold plate assembly that visually shows the structure the cold plate must conform to. 

Problem Statement

Problem Description

Specifications

· Achieve at least 140 W of cooling power for the whole system

· Must weigh less than 450 lb when filled with glycol

· Must operate between –20 C to 30 C

Final Deliverables to Client

· Verification of petal’s total cooling power obtained from our testing

· Finalized design of all 12 petals, complete with part files and drawings

· Submit FEA report detailing boundary conditions and results

· Final design report detailing design and test method

Requirements

· Develop a non-contacting cold plate that uses radiation as the primary form of heat transfer

· Test an “as-is” prototype that will be installed in the prototype

· Minimize temperature variances on the face sheet

· Must interface with existing telescope components

 

Constraints

· Must use 50% aqueous glycol solution

· Glycol will be 2.5 F below the ambient temperature

· Glycol will flow 2 GPM @ 10 psi