Act like a helpful tutor and exlain me :
Give step-by-step solution with explanation and final answer:Homework Question 3:
3.50 @3 Two kg. of water is contained in a piston-cylinder ‘assembly, initially at 10 bar and
200°C. The water is slowly heated at constant pressure to a final state. If the heat transfer for
the process is 1740 kJ, determine the temperature at the final state, in °C, and the work, in kJ.
Kinetic and potential energy effects are negligible.
Show the process in a P-v and T-v plot (v is in m*/kg). Just make representative plots like we did
. in the lectures, it need not be to scale.
I]
Question:
Act like a helpful tutor and exlain me :
Give step-by-step solution with explanation and final answer:Homework Question 3:
3.50 @3 Two kg. of water is contained in a piston-cylinder ‘assembly, initially at 10 bar and
200°C. The water is slowly heated at constant pressure to a final state. If the heat transfer for
the process is 1740 kJ, determine the temperature at the final state, in °C, and the work, in kJ.
Kinetic and potential energy effects are negligible.
Show the process in a P-v and T-v plot (v is in m*/kg). Just make representative plots like we did
. in the lectures, it need not be to scale.
I]
This is AI generated Response.
Asked by: manish kumar
Created at: 2025-10-05 00:08:25
Final Answer:
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Let's break down the problem **step-by-step**:
---
## **Given Data**
- Mass of water, \( m = 2\, \text{kg} \)
- Initial pressure, \( P_1 = 10\, \text{bar} \)
- Initial temperature, \( T_1 = 200^\circ \text{C} \)
- Heat added, \( Q = 174\, \text{kJ} \)
- Process: **Constant pressure** (isobaric)
---
## **Step 1: Find Initial Properties**
- Use steam tables for water at **10 bar** and **200°C**.
### At 10 bar:
- Saturation temperature, \( T_{sat} = 179.9^\circ \text{C} \)
- Since \( T_1 = 200^\circ \text{C} > T_{sat} \), water is **superheated**.
#### From steam tables (superheated, 10 bar, 200°C):
- \( h_1 = 2855.\, \text{kJ/kg} \)
- \( v_1 = .1944\, \text{m}^3/\text{kg} \)
---
## **Step 2: Energy Balance**
For a closed system undergoing a constant pressure process:
\[
Q = m(h_2 - h_1)
\]
Given \( Q = 174\, \text{kJ} \), \( m = 2\, \text{kg} \), \( h_1 = 2855.\, \text{kJ/kg} \):
\[
174 = 2(h_2 - 2855.)
\]
\[
h_2 = \frac{174}{2} + 2855. = 870 + 2855. = 3725.\, \text{kJ/kg}
\]
---
## **Step 3: Find Final State (\( h_2, P_2 \))**
- \( h_2 = 3725.\, \text{kJ/kg} \)
- \( P_2 = P_1 = 10\, \text{bar} \)
Check the **superheated steam tables** for \( h_2 \) at 10 bar:
- At 10 bar, 400°C: \( h = 3264.4\, \text{kJ/kg} \)
- At 10 bar, 600°C: \( h = 3762.8\, \text{kJ/kg} \)
\( h_2 = 3725.\, \text{kJ/kg} \) is between these values.
**Interpolate to find \( T_2 \):**
\[
T_2 = 400 + \frac{3725. - 3264.4}{3762.8 - 3264.4} \times (600 - 400)
\]
\[
= 400 + \frac{460.6}{498.4} \times 200
\]
\[
= 400 + .9243 \times 200
\]
\[
= 400 + 184.86 \approx 585^\circ\text{C}
\]
---
## **Step 4: Find Work Done**
At constant pressure,
\[
W = P(V_2 - V_1)
\]
\[
V = m \times v
\]
From steam tables at 10 bar and ~585°C:
- \( v_2 \approx .523\, \text{m}^3/\text{kg} \) (interpolated)
\[
V_1 = 2 \times .1944 = .3888\, \text{m}^3
\]
\[
V_2 = 2 \times .523 = 1.046\, \text{m}^3
\]
\[
W = P (V_2 - V_1) = (10 \times 10^5\, \text{N/m}^2) \times (1.046 - .3888)
\]
\[
= 1,000,000 \times .6572 = 657,200\, \text{J} = 657.2\, \text{kJ}
\]
---
## **Step 5: Plots (Sketches)**
### **P-v Diagram**
- A horizontal line at \( P = 10 \) bar,
- Moves from \( v_1 = .1944 \) to \( v_2 = .523 \) m³/kg.
### **T-v Diagram**
- A curve at increasing T,
- Moves from (200°C, .1944) to (585°C, .523).
---
## **Final Answers**
### **(a) Final Temperature**
\[
\boxed{T_2 \approx 585^\circ \text{C}}
\]
### **(b) Work Done**
\[
\boxed{W = 657.2\, \text{kJ}}
\]
---
## **Summary Table**
| State | P (bar) | T (°C) | h (kJ/kg) | v (m³/kg) | V (m³) |
|-------|---------|--------|-----------|-----------|---------|
| 1 | 10 | 200 | 2855. | .1944 | .3888 |
| 2 | 10 | 585 | 3725. | .523 | 1.046 |
---
## **Sketches**
### **P-v Plot**
```
P | _________
| /
|____/___________________ v
.1944 .523
```
### **T-v Plot**
```
T | /
| /
|____/___________________ v
.1944 .523
```
---
If you need the actual steam table values or more details on interpolation, just let me know!
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