Temperature drop calculation for pipelines and storage tanks
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Calculation 1: For a long time, we have been calculating the heat loss of insulated pipes, and various insulation standards do not take into account the temperature drop in pipes that are not insulated. Insulated pipes may not be common in industrial production, but such problems do exist in daily life. For example, my gas water heater is installed in the kitchen, and the distance from the kitchen to the bathroom is no more than 10 meters; therefore, the pipes should not be very long. Yet, when I turn on the faucet in the kitchen, the hot water is extremely hot, at around 60–70°C, while the hot water from the faucet in the bathroom is not hot at all, with a temperature of around 40 degrees Celsius. Can this large temperature difference be calculated using formulas, assuming that the pipes are exposed to the air? Several issues to be resolved: a. Common pipe materials: carbon steel and PVC. The thermal conductivity of steel can generally be found in manuals, but there is no particularly reliable data available for the thermal conductivity and emissivity of PVC pipes. b. How are the heat transfer coefficients for steel pipes, PVC pipes, and air calculated? Currently, the heat transfer coefficients specified in the insulation standards are based on formulas for insulation structures that include insulating materials and protective coatings on the surface. It is not clear whether these formulas can be applied to pipes that are exposed to the air. Someone gave me a thermal conductivity value of 0.23 for PVC, but the blackness value of PVC material is not available, making it impossible to calculate the heat transfer coefficient accurately. Therefore, I hope experts can offer some advice. Calculation II. Storage tanks are common devices in the industrial sector. The heat dissipation of such tanks is facilitated by three components: the vault, the cylinder, and the bottom plate. For the vault structure, no corresponding formula for calculating the heat transfer coefficient can be found; can the formula for flat plates be used instead? There are no accurate standards or methods available for calculating heat dissipation at the bottom of a tank. Some storage tanks have requirements regarding temperature drops; for example, the temperature drop within 24 hours must not exceed 2°C. It is urgent to carry out calculations in these two aspects, and I wonder how others address such issues.
I’m really curious too, same request :D:D:D:D
For calculations, reference can be made to HG/T20570.11-95； For calculations related to two, refer to Chapter 4 of the first volume of the \"Technical Manual for Oil and Gas Gathering and Transportation in Oil Fields\", which contains sections on tank insulation. In fact, heat transfer calculation involves determining the heat transfer coefficient, and the heat transfer coefficient is determined by considering five types of thermal resistances (the thermal resistance of the hot medium, the thermal resistance of the cold medium, the thermal resistance due to fouling on the surface of the hot medium, the thermal resistance due to fouling on the surface of the cold medium, and the thermal resistance of the heat transfer medium itself). It shouldn’t be difficult to analyze each of these components one by one.
Yes, the method for calculating the heat transfer coefficient is crucial
Question 1: Simple calculation, in accordance with SH/T3010_2013
The insulation thickness is 0; other parameters are not available, such as what are the thermal conductivity and emissivity values of PVC material?
Please refer to the formulas in SH/T3010_2013; the heat loss is related to factors such as the surface heat transfer coefficient, the temperature of the medium, and the ambient temperature. This applies to metal pipes, and it is a simple calculation – there’s no need to complicate things too much
What if it’s a PVC pipe? PVC material is definitely different from steel
I followed the methods or guidelines provided by the above-mentioned individuals, and to summarize: 1. There is no calculation for temperature drop due to lack of insulation in the pipes, and none of the insulation standards mention this； Because most applications in the industrial sector require insulation; the temperature drop in the absence of insulation was not taken into consideration ； 2. The temperature drop in oil tanks: I did a rough calculation, and without any heating measures, the temperature drop is quite significant. After checking the \"Technical Manual for Oilfield Oil and Gas Gathering and Transportation Design,\" it is indicated that heating facilities are generally provided ； Relying solely on insulation structures is no longer sufficient to meet the temperature drop requirements.
"The temperature drop in oil tanks: I’ve done a rough calculation, and without any heating measures, the temperature drop is quite significant. Relying solely on insulation structures is hardly sufficient to meet the requirements regarding temperature drops – this view is one-sided. In engineering design, if the allowable heat loss is not very low (i.e., the temperature drop is small), insulation is sufficient; the thickness of the insulation should be determined in accordance with SH/T3010_2013
The calculation of heat loss in light tubes is also necessary in engineering. For example, after being transported over long distances, a light tube’s temperature will drop when the ambient temperature is low; to maintain a constant temperature, a heater must be installed. When designing such a heater, it is necessary to calculate the heat loss of that light tube