параллакс фон
  • Thermal power: Pth = Qm x Cp x ?T
  • Required power: Pu = (Pth + loss heat) x 1.1
  • Installed power: Pi = Pu x (1 + voltage tolerance)?
  1. Watt density on tube sheath
Watt density CS

P = Power in W
S = Surface in cm?
CS = watt density in en W/cm?

SP
  1. Tube sheath T°C
Tube sheath

?T = T°C gap between tube sheath and medium in  °C
CS = watt density in en W/cm?
h = heat exchange coefficient in kcal/h*m?*°C

  1. T°C gap between wire and tube sheath
Temperature gap between wire

?T = T°C gap between wire and tube sheath in °C
P = Power from D1 to D2 in kW
D1 and D2 internal and external diameter
? = conduction coefficient in kcal/h*m*°C
L = cylinder length in m

CETAL engineers and expert define the watt density through an heat exchange software allowing to take into account all parameters.

CETAL software can effect detailed heat exchange calculations, the key outputs are:

  • Wire temperature
  • Tubular sheat tube temperature
  • Watt density
  • Pressure loss
  • Heat exchange coefficient

For basic design, please find below some references sorted by fluids.

  1. Water
    • Stagnant water, max load 8 — 12 W/cm?, material: copper, 321, 316L
    • Circulating water, max load 10 — 16 W/cm?, material: copper, 316L, inc 800, inc 825
    • Boric water, max load 8 W/cm?, material: 316L
    • Boiler water, max load 8 — 16W/cm?, material: 316L, inc 800, inc 825
    • Chlorated water, max load 6 W/cm?, material: inc 825
    • Sea water, max load 3,5 — 6 W/cm?, material: inc 825, inc 600
    • Demineralized water / deionized / distilled / softened, max load 4 — 6 W/cm?, material: 316L, inc 800, inc 825
    • Domestic hot water, max load 4 — 8 W/cm?, material: copper, 316L, inc 825
    • Caustic water (2%, 10%, <30%, 70%), max load 2,3 — 7 W/cm?, material: 316L, inc 825, inc 600
  2. Oil
    • Fuel oil pre-heating, light fuel oil, C fuel oil, max load 1 — 2 W/cm?, material: 321, 316L
    • Heavy fuel, max load 0,5 — 3,5 W/cm? acc to grade, material: 316L
    • Gasoline, kerosene, max load 3,0 — 3,5 W/cm?, material: 316L
    • Machine oil SAE 10, 30, 40 & 50, max load 2,0 — 3,5 W/cm?, material: 316L
    • Mineral oil , max load 0,5 — 3,5 W/cm? acc to temp, material: 321, 316L
    • Lube oil, max load 2,3 W/cm?, material: 321, 316L
  3.  Acid & corrosive fluid
    • Acetic acid, max load 6W/cm?, material: 316L, inc 825
    • Boric acid, max load 6W/cm?, material: inc 825
    • Chloric, hydrofluoric, nitric, sulphuric acide, max load 1,5W/cm?, material: teflon coat
    • Boric acide, max load 6W/cm?, material: inc 825
    • Alkaline bath, max load 6W/cm?, material: 321 (no corrosive compound), 316L
    • Phosphate bath, max load 4W/cm?, material: 316L, inc 825
  4. Glycol
    • Ethylene glycol, propylene glycol, 4 to 8 W/cm? acc. to concentration, material: 321, 316L
  5. Others
    • Asphalt, tar, and other heavy or highly viscous compounds, max load 0,5 — 1,5W/cm?, material: 316L
    • Milk, max load 0,3W/cm?, material: 316L
  6. Gas
    • Air, max load 0,1 — 8W/cm? acc. to sheath temp, material: 321
    • Circulating air, max load 0,1 — 8 W/cm? acc. to sheath temp, material: 309
    • Natural gas, max load 0,1 — 8 W/cm? acc. to sheath temp, material: 321, 316L
    • Argon, nitrogen, W/cm? acc. to sheath temp, material: 321, 316L, inc 825, inc 600
    • Propan, Butane, W/cm? acc. to sheath temp, material: 321, 316L
    • Oxygen, Hydrogen, W/cm? acc. to sheath temp, material: 316L
  7. Solids
    • Aluminium, brass, bronze cast in, max load 4 — 15W/cm?, material: 309
    • Copper-nickel cast in, max load 5 — 10W/cm?, material: 309
    • Oxychloration, max load 3 W/cm?, material: inc 800, inc 825
    • Calcination, max load 3 W/cm?, material: inc 800, inc 825
Inputs

  • ATEX or Not
  • Fluid type
  • Pressure (in bars)
  • T°C In and Out (in °C)
  • Flow rate (kg/h or Nm3/h)
  • Surroundings
  • Voltage (V)
  • Standards?
 Outputs

  • Power
  • Watt density
  • Tube sheath material & ?
  • Product type and technology
  • Dimension (HL, CL, SOL)
  • Control and safety
  • Components choice
  • Price & leadtime