by A thesis submitted to the University of Plymouth in ... - PEARL home

various building materials at the University of
Plymouth, in thermally controlled, laboratory
conditions (Goodhew and Griffiths, 2004,2005).
Three unknowns exist in the established equation
(4) that represents the heating curve of the probe
during a measurement cycle: thermal conductivity
(; ý); thermal diffusivity (a); and a property with
notation H, which has not been defined absolutely
Figure 2: A Hukseflux
but is usually taken to denote the reciprocal of
TP08 thermal probe
contact resistance between the probe and sample
material, sometimes termed probe conductance. Further explanation of
equation (4) is given in chapter 2, the literature review, indexed there in two
forms as equations (7) and (14), and in a further form in chapter 4, indexed
there as equation (33).
2A
lný 4a. t
7+ +r lný 4a. 1 a. MPC 4a. 1
AT -- In
22Y+I-2P 2
Y+
2A
ýJ+Oýr
4, TA rrH 2a. 1 r )r. r rrHa. t
2
Equation (4)
Apart from these three unknowns in equation (4), many other unknowns were
foreseen in taking forward the previous laboratory work, regarding the practical
application
of the thermal probe approach. These included: the effect of
reduced contact between the probe and sample with the varying hole diameters
envisaged when drilling coarse materials; the effects of different fillers used to
improve contact; lack of or incomplete fillers; and whether heat from the hole
drilling process or heating cycles would cause sufficient moisture migration,
10