Maximizing Efficiency: Temperature Control in Concrete Slabs

How can we optimize temperature control in concrete slabs?

What is the ideal temperature difference between the heater surface and the slab surface to minimize thermal stress in concrete?

Answer:

The ideal temperature difference between the heater surface (T1) and the slab surface (T2) to minimize thermal stress in concrete should not exceed 16°C.

One effective method to optimize temperature control in concrete slabs is by ensuring that the temperature difference between the heater surface and the slab surface does not exceed 16°C. This is crucial in minimizing thermal stress in the concrete, which can lead to cracks and structural damage over time.

By following the guidelines from the 2015 ASHRAE Handbook—HVAC Applications, Chapter 51, we can formulate the temperature profile in the concrete slab and determine the thickness of the concrete slab (L) to maintain T1 - T2 ≤ 16°C.

According to Fourier's law for heat conduction on a plate, the heat conducted per unit of time and surface is q = -k/t * ΔT, where k represents thermal conductivity, t represents thickness, and ΔT represents temperature difference. Rearranging the equation, we can calculate the thickness required as t = -k/q * ΔT.

Substituting the given values of thermal conductivity (1.4 W/m⋅K), heat provided by the heating cable (1200 W/m2), and maximum temperature difference (16°C), we can determine that the thickness of the concrete slab should be 18.7 mm to maintain the desired temperature control without exceeding the thermal stress limit.