How to set up the balance equation

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Discussion Overview

The discussion revolves around setting up a balance equation for a problem involving phase changes and heat transfer, specifically related to a system containing ice and liquid water under certain pressure conditions. Participants seek clarification on how to incorporate the ice into the balance equation and address related concepts such as fusion heat.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses difficulty in applying the balance equation for problems 7-2 and 7-3, specifically mentioning the need for an additional term for the ice.
  • Another participant describes the conditions in problem 7-2, noting the importance of having enough ice to cool the liquid water while maintaining pressure limits in the containment.
  • The same participant explains the process of heating the ice to its melting temperature, changing phase, and then reaching equilibrium with the primary water.
  • A participant raises a concern about how to set up the balance equation, particularly regarding the inclusion of ice and the concept of fusion heat.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on how to set up the balance equation, and multiple competing views on the approach to incorporating ice and fusion heat remain unresolved.

Contextual Notes

There are limitations regarding the assumptions made about the volume of ice and its phase changes, as well as the specific conditions under which the balance equation is to be applied.

matt222
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I have problem with these two questions, can you give me a hint and help to understand it, I do understand problem 7-3 but i have problem with applying the equastion, I don't understand to 7-2 but i knw we have to have an addition term for the ice in the given balance equastion, can anyone help me with it


here its sorry
 

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matt222 said:
I have problem with these two questions, can you give me a hint and help to understand it, I do understand problem 7-3 but i have problem with applying the equastion, I don't understand to 7-2 but i knw we have to have an addition term for the ice in the given balance equastion, can anyone help me with it
I don't see problem 7-2.
 


the attachment corrected
 


In 7-2, there is containment at a given volume and pressure (1 atm). If there is a rupture of the primary system (initially at saturated liquid conditions at 15.5 MPa), it will pressurize the containment. There has to be enough ice available to cool the liquid water from the primary system, such that the vapor and air in the containment do not exceed the pressure limit of 0.4 MPa.

The ice is at -10°C, so it must heat up to melting temp, then change phase from liquid to solid, and then heat up to some equilibrium with the primary water.

One can neglect the volume of ice by assuming that it's volume doesn't change much going from ice to liquid in containment.
 


But the problem now how to set up the balance equation! How to include the ice in the equation and we have fusion heat mixed me up!
 

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