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Heat conduction is one of the three basic forms of heat transfer. According to the second law of thermodynamics, heat is always transferred from the higher energy level to the low energy level.
WL 422 offers basic experiments for targeted teaching on the topic of heat conduction in fluids. Such teaching should discuss the fundamental differences between gases and liquids.
Two cylinders form the main component of the experimental unit: an electrically heated inner cylinder situated in a water-cooled outer cylinder. There is a concentric annular gap between the two cylinders. This annular gap is filled with the fluid being studied. The heat conduction occurs from the inner cylinder, through the fluid to the outer cylinder. The narrow annular gap prevents the formation of a convective heat flux and allows a relatively large pass-through area while at the same time providing a homogeneous temperature distribution.
The experimental unit is equipped with temperature sensors inside and outside of the annular gap. Thermal conductivities for different fluids, e.g. water, oil, air or carbon dioxide can be determined in experiments.
The microprocessor-based instrumentation is well protected in the housing. The GUNT software consists of a software for system operation and for data acquisition and an educational software. With explanatory texts and illustrations the educational software significantly aids the understanding of the theoretical principles. The unit is connected to the PC via USB.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
Steady heat conduction in gases and liquids:
- determine the thermal resistance of fluids
- determination of thermal conductivities k for different fluids at different temperatures
Transient heat conduction in fluids:
- interpret transient states during heating and cooling
- introduction to transient heat conduction with the
block capacity model
 investigation of the thermal conductivity of common fluids, e.g. water, oil, air or carbon dioxide
 concentric annular gap between 2 cylinders containing the fluid being studied
 inner cylinder, continuously electrically heated
 water-cooled outer cylinder
 display of temperatures and heating power in the display
 microprocessor-based instrumentation
 functions of the GUNT software: educational software, data acquisition, system operation
 GUNT software via USB under Windows Vista or Windows 7
- heating power: 350W
- height: 0,4mm
- average diameter: 29,6mm
- mass: 0,11kg
- specific heat capacity: 890J/kg*K
- temperature: 2x 0...325°C
- heating power: 0...450W
Dimensions and Weight
Weight: approx. 18kg Required for Operation 230V, 50Hz, 1 phase
Cold water supply: max. 30°C, min. 1L/h
Scope of Delivery
1 experimental unit
1 CD with authoring system for GUNT educational software
1 CD with GUNT software + USB cable
1 set of instructional material