1. The total enthalpy of 15.000kg of steam at 2250.000kPa is 34191.510kJ. Determine the dryness of the steam.
ANS = %
2. Determine the quantity of heat required, to raise 11.100kg of water at 80.000 degrees Celsius, to saturated steam at 2250.000kPa and 71.400% dry.
ANS = kJ
Not sure where to start. I need a little help please. I do have a chart with the properties of saturated steam. Thank you.
To solve these questions, you will need to use the properties of steam and understand the concept of enthalpy and saturation. Here is a step-by-step guide to solving each question:
Question 1: Determining the dryness of the steam
1. First, find the enthalpy of saturated steam at the given pressure (2250.000kPa) by referring to the chart you have. The enthalpy of saturated steam is usually given in kJ/kg.
2. Next, calculate the total enthalpy of the steam using the formula: Total Enthalpy = Dryness Fraction × Enthalpy of Saturated Steam.
3. Rearrange the formula to solve for the dryness fraction: Dryness Fraction = Total Enthalpy / Enthalpy of Saturated Steam.
4. Plug in the given values of the total enthalpy (34191.510 kJ) and the pressure to find the dryness fraction. Multiply this value by 100 to convert it to a percentage to get the answer.
Question 2: Determining the quantity of heat required
1. First, find the enthalpy of saturated liquid water at the initial temperature of 80.000 degrees Celsius. Look up this value in the chart you have.
2. Calculate the change in enthalpy from the initial state (water) to the final state (saturated steam). Use the formula: Change in Enthalpy = (Enthalpy of Saturated Steam - Enthalpy of Saturated Liquid Water) × Mass of Water.
3. Plug in the given values of the initial temperature, pressure, and the mass of water to calculate the change in enthalpy.
4. Rearrange the formula to solve for the quantity of heat required: Quantity of Heat = Change in Enthalpy / Dryness Fraction.
5. Plug in the given values of the dryness fraction and the change in enthalpy to find the answer.
Remember to use the appropriate units and conversions in your calculations. By following these steps and using the chart of steam properties, you should be able to solve both of these questions.