Chapter 4 - Critical Design Aspects and Performance Capabilities of Cryocoolers and Microcoolers with Low Cooling Capacities

Abstract

This chapter addresses critical design issues of cryocoolers and microcoolers, with an emphasis on efficiency, reliability, and power consumption. It discusses the design aspects of cryocoolers used in commercial, scientific, space, and military applications. It describes closed-cycle cryocoolers in detail because of their proven performance including their cost-effective operation, stealthy design, and reliability. It also summarizes the performance capabilities of stirling cryocoolers. The maintenance aspects of cryocoolers are briefly discussed with particular emphasis on reliability, loss of cryogen, and freedom of refill. Boreas-cycle cryocoolers, which use both the high-pressure ratio and counterflow heat exchanger, are described with specific details on performance level and reliability. The chapter also discusses microcooler and cryocooler designs incorporating advanced material technology and unique heat exchanger configurations. Performance capabilities and limitations of widely used cryocoolers are briefly described with an emphasis on heat lead, reliability, and input power requirement. Potential cooling schemes—conduction, convection, and radiation—are discussed with an emphasis on temperature differential and thermal efficiency.