Heat dissipation calculation for insulated pipes
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I would like to ask fellow users for guidance on calculating the heat loss of insulated pipes: For a DN80 pipe with 50mm of rock wool insulation, containing hot water at 95 degrees Celsius, with a length of 35 meters and an ambient temperature of 25 degrees Celsius, what is the hourly heat loss? How to calculate it? I hope the experienced sea friends can provide the calculation sheet; thank you very much!
To calculate the heat loss per hour for a DN80 insulated pipe, the following steps can be used for estimation: 1. **Determine the heat transfer parameters**: - **Inner diameter** (the inner diameter of DN80 is approximately 80 mm) - **Outer diameter** (inner diameter + 2 layers of rock wool thickness, i.e., 80 mm + 2*50 mm = 180 mm) - **Thermal conductivity of the insulation material** (rock wool has a value of around 0.04 W/m·K) 2. **Calculate the heat transfer area**: - The external surface area \(A\) of the pipe can be calculated using \(A = \pi \times d_{\text{outer}} \times L\), where \(d_{\text{outer}}\) is the outer diameter and \(L\) is the length of the pipe. Substituting the values gives: \ 3. **Calculating the total thermal resistance**: - The thermal resistance \(R\) is composed of the convective thermal resistance of the inner surface, the thermal conduction resistance of the rock wool, and the convective thermal resistance of the outer surface. Generally, the convective heat resistance at the surface is relatively high, allowing for simplified estimation; here we first calculate the thermal conduction resistance of the insulation layer: \ where \(k\) is the thermal conductivity of rock wool. Substituting the values gives: \ 4. **Calculating heat dissipation**: - Use the formula \(Q = \frac{\Delta T}{R}\), where \(\Delta T\) is the temperature difference between the inside and outside of the pipe (95°C - 25°C = 70°C). Substituting the values gives: – To convert the above value in watts to the heat dissipated per hour: \(Q_{\text{hour}} = 5.65 \text{ W} \times 3600 \text{ s/h} \approx 20340 \text{ J/h}\) This is a simplified calculation; the actual value may vary depending on the convective heat resistance of the pipe surface and the environmental conditions. If more accurate calculations or detailed calculation sheets are required, it is recommended to use professional thermal design software for simulation. .
Thank you very much for your reply. Could you provide the specific mathematical formulas (not in a computer language)? What is the final calculation result? I earnestly request a reply; thank you very much!
The original design of the pipeline can be viewed； And it is also possible to view HG/T-20229-2017 – Specifications for the Construction and Acceptance of Anti-corrosion Works on Chemical Equipment and Pipelines