If you peruse Google for Earth cooling rates, you might find what you're looking for. Here's one of many sources. I strongly recommend reading the entire page,as it discusses some of the geology-based estimates as well.
Kelvin's primary attack on geologic dating was that measurements of
the rates of geologic processes were highly uncertain, if it was
possible to measure them at all (Hallam, 110). Accordingly, Kelvin
sought to apply the knowledge of physics to the problem. Given that
temperature increases the further one descends below Earth's surface,
Kelvin concluded that Earth was slowly cooling. He set out to
calculate the time required for the Earth to cool, and thereby
solidify, from an initially molten state. The idea that Earth had
begun as an incredibly hot sphere of liquid dates back to Descartes
and Leibnitz. This assumed initial condition was the linchpin for
Kelvin's entire method (Hallam, 110). Bits of material at the surface
would sink before solidifying, creating convection currents that kept
the Earth at a uniform temperature until solidification began at the
core (Hallam, 110; Knopf, 445). Kelvin needed to know: (1) the
temperature at Earth's core, (2) the temperature gradient with regard
to depth below the surface, and (3) the thermal conductivity of rocks.
The gradient was established to be around one degree Fahrenheit for
every fifty feet. Kelvin made his own measurements of conductivity.
The problem was determining the temperature at the core. This is where
Kelvin's theory of solidification enters the picture. Because the core
was thought to be solid rock, its temperature could not exceed the
melting point of rocks (Hallam, 110). He constructed the following
dθ / dx = S / h √(π t)
The temperature gradient is expressed by dθ / dx; h is the thermal
conductivity; x is the distance below the surface, and θ is the
temperature (Holmes, 445). In 1862, Kelvin arrived at a likely age of
100 million years. Because of uncertainties in the data, the lower and
upper limits were 20 million and 400 million years (Dalyrmple, 26;
That said, there are plenty of more recent papers which estimate the cooling rates (with and without the help of the radioactive elements) based on the kinds of data now available as to the current and historical makeup of the core, mantle, and outer layer(s), heat transfer cycles, etc.