1

Development of CryoTel® DT Cryocooler

S. Kim1, E. Holliday1, R. Unger2, R Wiseman2

1Sunpower Inc., Athens, OH 45701 2 Consultants

ABSTRACT

A small split-type Stirling cryocooler, CryoTel® DT, has been developed for small and portable systems, where small size, light weight and low vibration signature become important. The split cold head equipped with a small passive balancer is coupled to a dual-opposed pressure wave generator in which two opposing twin pistons cancel the vibration of each other. The heat lift measured in the lab tests was 2.3 W at 77 K with 30 We of input power and 2.7 W at 77 K with 40 We, and the COP achieved a new record, 15% higher than that of the previous best efficiency CryoTel® CT. Three hermetically-sealed DT cryocoolers were built and tested in a certain customer’s facility for the qualification. The test results confirmed that the DT cryocoolers were qualified by exceeding the performance specifications and satisfying all of the other requirements. The vibration acceleration of the cold head was also measured at less than 40 mG. This paper presents the features and the performance test data of the new cryocooler.

INTRODUCTION

The CryoTel® DT is a small split-type Stirling cryocooler driven by a dual-opposed pressure wave generator that is a new addition to Sunpower’s commercial product line-up. The current CryoTel® models: the MT, CT, and GT are integral-type Stirling cryocoolers provide high performance, low cost and long life operation1,2. The CryoTel® family of cryocoolers, based on Sunpower’s innovative technologies of free piston, linear motor, and non-contact gas bearing, offers unique solutions to various applications in the market and builds a solid reputation for unrivaled performance and quality.

The new cryocooler DT is an extension of the CryoTel® family that is designed to satisfy the following major requirements as requested by a specific customer: cooling capacity (heat lift, greater than 1.5 W at 77 K), light weight (total mass, lighter than 1.5 kg), small size (outside diameter, less than 3”), and low vibration. As shown in Figure 1, a split configuration along with a dual-opposed pressure wave generator was chosen for the inherent reduction of the vibration signature. The remaining vibration of the cold head is attenuated by a small passive balancer. Subsequently, another application for higher cooling power was added by the customer, which eventually resulted in two different CryoTel® DT cryocoolers, the DT55 and the DT60.

Sunpower launched the development program in 2011 and shipped three hermetically-sealed DT cryocoolers to a customer for the qualification test in early 2012. All of them passed the test and exceeded the requirements. The hermetically-sealed CryoTel® DT55 consists of a cold head

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2 102 MEDIUM-CAPACITY 50-80 K SINGLE-STAGE CRYOCOOLERS

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3 103THE DEVELOPMENT OF CRYOTEL® DT CRYOCOOLER

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REFERE 1. Unge

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power has er driven bymatically love passed th

in 2013.

ENCES er, R., Keiterneering, Voler, R., “The Amer. Institueon, D., SAGociates, Athen

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owered whihe qualifica

r, D., “The dl. 49B, Amerdevelopment

ute of PhysicsGE User’s Gns, OH, 2011

e 5. CryoTel®

ly developpposed presile maintaination tests

developmentr. Institute oft of the Cryos, Melville, N

Guide, Stirlin1.

® DT60 Perf

ped the Crssure wave ning the unof a certain

t of the Cryof Physics, MoTelTM LT NY (2006), pg, Pulse-tub

formance Te

ryoTel® Dgenerator.

nrivaled pen customer

oTelTM famelville, NY (and GT,” Ad

pp. 1719-172be and Low-

est Data

DT, a smalThe vibrati

erformance. r and the n

mily of coole(2004), pp. 1dv. in Cryog25. T Cooler M

ll split-typeion of the c

The pre-pnew product

ers,” Adv. in 401-1404.

genic Enginee

Model Classic

e Stirling cold head

production ts will be

Cryogenic

ering, Vol.

cs, Gedeon

5 105THE DEVELOPMENT OF CRYOTEL® DT CRYOCOOLER