Subject: Help with Cryocooler Cold Tip Temperature Simulation

Hi everyone!

I’m trying to simulate the temperature change of a cryocooler’s cold tip in response to varying heat loads. Most cryocoolers have a performance curve that shows the relationship between heat load and cold tip temperature, and I’m attempting to create a simplified model of this behavior.

Model Setup

I’ve built a basic assembly where:

• The bottom part represents a simplified model of the cryocooler’s cold tip.

• The upper part is a copper object that needs to be cooled.

The cold tip temperature depends on the thermal interaction with the middle surface of the assembly. I’ve defined this dependency using a table (see below).

Problem

When I run the simulation, instead of observing a gradual temperature decrease at the cold tip over time, I see oscillations in both temperature and heat flow rate (screenshot attached). This doesn’t seem physically correct—I’d expect a smooth transient response.

Has anyone encountered similar issues? Any suggestions on how to stabilize the simulation or adjust the model settings?

Attachments:

1. Dependency table (heat load vs. temperature)

2. Graph showing temperature/heat flow oscillations

Thanks in advance for your help!

Datasheet graph for cryocooler

Simplified model cryocooler(cold tip is bottom part)

Table which i made for temperature dependency 

Oscilations of temperature