23. Transient Heat Transfer from an Infinitely Long and Thin Heat Source used to Measure Thermal Conductivity of Soils and Soft Rocks in an Infinite Cylindrical Medium Available to Purchase

Thermal conductivity of soils and soft rocks is an important thermophysical property used in models for climate change and for crop production. In this chapter, we will investigate transient heat transfer from an infinitely long and thin heat source, called the thermal needle probe, to an infinite cylindrical medium to determine the temperature rise in the medium with increasing time. We will show that the temperature-rise versus natural logarithm of time, Ln(θ), for the medium can be linearly correlated at large times. The transient heat transfer equation that applies to this case is given in radial coordinates with its initial and boundary conditions in Equations 23-1.