Seeking advice

This post was last edited by Qingcheng Jun on 2022-3-2 09:11: “System at 90°C”? Do you understand what this sentence means? This sentence means that it is an adiabatic system, and the temperature of both the gas and liquid phases is 90 degrees. Under actual operating conditions, when the gas phase is not insulated, the system exhibits a temperature gradient; failing to take this into account has a significant impact on the calculations. The saturated vapor pressure of water at 90 degrees is less than 100 kPa. Additionally, the pressure resulting from the thermal expansion of the air isn’t clearly specified, and the title isn’t changed to something that reflects the actual content of the question – everything shows signs of carelessness and haste

It is recommended to break down the problem into more specific parts. For example, it includes a flowchart, along with the conditions of use, the objectives to be achieved, and the existing problems. It’s probably the problems caused by lack of sleep, right?:)

Is it a practical engineering problem or a purely academic discussion?

I’m sorry; my explanation wasn’t clear enough. The volume of this storage tank is 5 cubic meters. After the system has been purged with nitrogen, a slight positive pressure is maintained. Now, 2 tons of pure water are added to this tank. Once that is done, nitrogen is used to keep the pressure in the tank at 500 PAG. The temperature of the pure water inside the tank is equal to the ambient temperature; let’s assume it’s 25 degrees Celsius. Now, the tank is heated so that the temperature inside it reaches 90 degrees Celsius. During this heating process, the vent valve remains closed. What is the pressure in the storage tank at 90°C?

This is interesting; proportionally, if a 5m3 tank contains 2m3 of water, then the temperature measured by the temperature probe should correspond to that of nitrogen, which is at a pressure of 90°C... That’s not the temperature of the water.

It shows what value there is in professional questions posed by unprofessional people. It’s not clear whether the temperature refers to the water temperature or the nitrogen temperature; if it’s the water temperature, then the nitrogen temperature is also unknown. It’s estimated to be between 70-100 kPa

If you’re going to answer, then answer; if not, get lost

In this storage tank, what do you think is the temperature difference between nitrogen and water? I’m not professional, so how professional are you? Which tank do you see where both the liquid and the gas space above it need to be equipped with thermometers? If you’re going to answer, then answer. If not, get as far away from me as you can

Stay calm. This question isn’t actually that difficult. What you’ve described is a bit vague; there’s only one temperature sensor in the diagram, and it measures the temperature of nitrogen, not that of water. There’s a big difference; after all, this is a technical forum, so everyone is very serious. Qingcheng also has good intentions; otherwise he wouldn’t reply. He hopes to help you solve this problem as well, but since the issue is not clear, he’s just worried on your behalf. To speak separately, both gas spaces and liquid spaces can accommodate temperature probes; this is determined by the operating conditions and intended use. In the case of experiments, it is quite normal to use seven or eight probes. In an adiabatic condition, if the liquid is at 90 degrees, the temperature of the gas space is not necessarily 90 degrees. The forum is full of people in the tech field; even there’s a big difference between those from 1990 and 1991. Because there is nitrogen as well as unsaturated water vapor in the gas space, it is a more complex situation, not a condition involving only pure elements. Please describe it as clearly as possible; everyone, help out. Try not to rush; it’s early in the morning, and things aren’t easy either.