Question 1

Kako se debljina izolacije izračunava za ravnu površinu?

Accepted Answer

For a flat surface: thickness = k × (T_hot − T_surface) / q, where k is thermal conductivity of insulation, T_hot is process temperature, T_surface is desired surface temperature, and q is heat flux. The surface heat transfer coefficient h_out also plays a role: q = h_out × (T_surface − T_ambient).

Question 2

Kako se proračun izolacije cijevi razlikuje od ravnih površina?

Accepted Answer

Pipe insulation uses the cylindrical heat transfer equation with logarithmic radius ratio: Q/L = 2π(T_hot − T_ambient) / [1/(h_in·r_i) + ln(r_o/r_i)/k_pipe + ln(r_ins/r_o)/k_ins + 1/(h_out·r_ins)]. The curved geometry means more insulation material is needed per unit of thermal resistance.

Question 3

Koja je tipična toplinska vodljivost izolacije?

Accepted Answer

Mineralna vuna: 0.035–0.045 W/mK. Staklena vuna: 0.030–0.040 W/mK. Poliuretanski pjena: 0.022–0.028 W/mK. Kalcijev silikat: 0.055–0.070 W/mK. Aerogel: 0.013–0.020 W/mK. Niža k = bolji izolator.

Question 4

Koja je temperatura površine sigurna za zaštitu osoblja?

Accepted Answer

For personnel protection, maximum surface temperature should be ≤60°C (140°F) according to most industrial standards. Some standards require ≤50°C for surfaces accessible to workers. This prevents burns from brief contact.

Question 5

Ima li koeficijent prijenosa topline vanjske površine utjecaja?

Accepted Answer

Yes. The outer film coefficient h_out (typically 5–25 W/m²K) affects the surface temperature. Still air: ~5–10 W/m²K. Light wind: ~15 W/m²K. Forced convection: 20–50 W/m²K. Lower h_out means higher surface temperature for same insulation.

Kalkulator debljine izolacije

Results

Flat Surface

Cijev / Cilindra