Give step-by-step solution with explanation and final answer:1 - Fill the following table. Show your calculations for specific volume.
T(C) Specific Vol (for Density | Reference for Data Source
saturated condition take
x =0.5)
RI34A(sat) | f400 | [~~]
[Nw3 [| -ofa000 [|]
[cca [ 2000 [| 0]
2 - Water initially at 200 kPa and 300°C is contained in a piston-cylinder device fitted with stops. The water is
allowed to cool at constant pressure until it exists as a saturated vapor and the piston rests on the stops. Then the
‘water continues to cool until the pressure is 50 kPa. On the 7-v diagrams sketch, with respect to the saturation lines,
the process curves passing through both the initial, intermediate. and final states of the water. Label the 7, P and v
values for end states on the process curves. Find the overall change in internal energy and work of water between the
initial and final states per unit mass of water.
—
Water
200 kPa 0
300°C
Question:
Give step-by-step solution with explanation and final answer:1 - Fill the following table. Show your calculations for specific volume.
T(C) Specific Vol (for Density | Reference for Data Source
saturated condition take
x =0.5)
RI34A(sat) | f400 | [~~]
[Nw3 [| -ofa000 [|]
[cca [ 2000 [| 0]
2 - Water initially at 200 kPa and 300°C is contained in a piston-cylinder device fitted with stops. The water is
allowed to cool at constant pressure until it exists as a saturated vapor and the piston rests on the stops. Then the
‘water continues to cool until the pressure is 50 kPa. On the 7-v diagrams sketch, with respect to the saturation lines,
the process curves passing through both the initial, intermediate. and final states of the water. Label the 7, P and v
values for end states on the process curves. Find the overall change in internal energy and work of water between the
initial and final states per unit mass of water.
—
Water
200 kPa 0
300°C
This is AI generated Response.
Asked by: Veera manikanta
Created at: 2025-09-03 20:56:30
Final Answer:
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Let's break down the solution into two parts as per your questions.
---
## **1. Filling the Table**
We'll use thermodynamic property tables (Steam Tables, Refrigerant Tables, etc.) to find the specific volume at the given conditions (for saturated cases at x=0.5, which means a mixture with quality = 0.5).
#### **a) Water (saturated), T = 200°C**
- At T = 200°C, the saturation pressure (\(P_{sat}\)) is approximately **1554 kPa**.
- Specific volume at x = 0.5:
- \( v = v_f + x(v_g - v_f) \)
- From steam tables: \( v_f \approx 0.001157 \) m³/kg, \( v_g \approx 0.12721 \) m³/kg
\( v = 0.001157 + 0.5 \times (0.12721 - 0.001157) = 0.001157 + 0.5 \times 0.126053 = 0.001157 + 0.0630265 = 0.06418 \) m³/kg
- Density (\( \rho \)) = \( \frac{1}{v} \) = \( \frac{1}{0.06418} \approx 15.59 \) kg/m³
- **Reference:** Steam Tables
---
#### **b) R-134A (saturated), P = 400 kPa**
- At P = 400 kPa, T ≈ 18.87°C
- \( v_f \approx 0.000887 \) m³/kg, \( v_g \approx 0.05426 \) m³/kg
\( v = 0.000887 + 0.5 \times (0.05426 - 0.000887) = 0.000887 + 0.026687 = 0.027574 \) m³/kg
- Density = \( \frac{1}{0.027574} \approx 36.25 \) kg/m³
- **Reference:** R-134a Property Tables
---
#### **c) R-22 (saturated), T = 40°C**
- At T = 40°C, P ≈ 1550 kPa
- \( v_f \approx 0.000911 \) m³/kg, \( v_g \approx 0.01743 \) m³/kg
\( v = 0.000911 + 0.5 \times (0.01743 - 0.000911) = 0.000911 + 0.0082595 = 0.009170 \) m³/kg
- Density = \( \frac{1}{0.009170} \approx 109.0 \) kg/m³
- **Reference:** R-22 Property Tables
---
#### **d) NH3, T = -10°C, P = 1000 kPa**
- At T = -10°C, P ≈ 328 kPa (saturation), but given P = 1000 kPa (so it is subcooled liquid).
- At P = 1000 kPa, T_sat ≈ 29.75°C. At T = -10°C, use subcooled liquid properties (same as saturated liquid at -10°C).
- \( v_f \approx 0.001638 \) m³/kg
- Density = \( \frac{1}{0.001638} \approx 610 \) kg/m³
- **Reference:** NH3 Property Tables
---
#### **e) CO2, T = -20°C, P = 1000 kPa**
- At T = -20°C, P_sat ≈ 1740 kPa. Given P = 1000 kPa (so it is a mixture).
- At -20°C, \( v_f \approx 0.000977 \) m³/kg, \( v_g \approx 0.1941 \) m³/kg
\( v = 0.000977 + 0.5 \times (0.1941 - 0.000977) = 0.000977 + 0.0965615 = 0.09754 \) m³/kg
- Density = \( \frac{1}{0.09754} \approx 10.25 \) kg/m³
- **Reference:** CO2 Property Tables
---
### **Filled Table**
| Substance | T (°C) | P (kPa) | Specific Vol (m³/kg) | Density (kg/m³) | Reference |
|----------------|--------|---------|----------------------|-----------------|-------------------|
| Water (sat.) | 200 | 1554 | 0.06418 | 15.59 | Steam Tables |
| R-134A (sat.) | 18.87 | 400 | 0.02757 | 36.25 | R-134a Tables |
| R-22 (sat.) | 40 | 1550 | 0.00917 | 109.00 | R-22 Tables |
| NH3 | -10 | 1000 | 0.001638 | 610 | NH3 Tables |
| CO2 | -20 | 1000 | 0.09754 | 10.25 | CO2 Tables |
---
## **2. Thermodynamics Problem Solution**
**Given:**
- Initial state: \( P_1 = 200 \) kPa, \( T_1 = 300^\circ \)C
- Cool at constant pressure until it is a saturated vapor (\( x = 1 \)), then cools further at constant volume (piston on stops) until \( P_3 = 50 \) kPa.
### **Step 1: Initial State (1)**
- \( P_1 = 200 \) kPa, \( T_1 = 300^\circ \)C
- From steam tables, at P = 200 kPa:
- \( T_{sat} = 120.23^\circ \)C (lower than 300°C, so it is superheated vapor)
- Find specific volume \( v_1 \) and internal energy \( u_1 \):
From superheated steam tables:
- At 200 kPa, 300°C: \( v_1 = 1.5490 \) m³/kg, \( u_1 = 2725.5 \) kJ/kg
---
### **Step 2: Intermediate State (2) (Saturated vapor at 200 kPa, x=1)**
- \( P_2 = 200 \) kPa, \( x_2 = 1 \) (saturated vapor)
- From steam tables at 200 kPa:
- \( T_2 = T_{sat} = 120.23^\circ \)C
- \( v_g = 0.88578 \) m³/kg, \( u_g = 2506.5 \) kJ/kg
---
### **Step 3: Final State (3) (P = 50 kPa, v = v_2)**
- The piston rests on stops, so **volume is constant**: \( v_3 = v_2 = 0.88578 \) m³/kg
- At \( P_3 = 50 \) kPa, find the phase:
- At 50 kPa: \( v_f = 0.001012 \) m³/kg, \( v_g = 12.674 \) m³/kg
- \( v_3 = 0.88578 \) m³/kg is between \( v_f \) and \( v_g \), so it is a mixture.
- Quality \( x_3 = \frac{v_3 - v_f}{v_g - v_f} = \frac{0.88578 - 0.001012}{12.674 - 0.001012} \approx \frac{0.88477}{12.673} \approx 0.0698 \)
- Internal energy at 50 kPa:
- \( u_f = 209.33 \) kJ/kg, \( u_g = 2584.7 \) kJ/kg
- \( u_3 = u_f + x_3(u_g - u_f) = 209.33 + 0.0698 \times (2584.7 - 209.33) \)
- \( = 209.33 + 0.0698 \times 2375.37 = 209.33 + 165.82 = 375.15 \) kJ/kg
---
### **Step 4: Find the changes**
#### **a) Change in Internal Energy (\( \Delta u \))**
\( \Delta u = u_3 - u_1 = 375.15 - 2725.5 = -2350.4 \) kJ/kg
#### **b) Work Done**
- Work done during the constant pressure process (1→2):
\( W_{1-2} = P (v_2 - v_1) = 200 \times 10^3 (0.88578 - 1.5490) = 200,000 \times (-0.66322) = -132,644 \) J/kg \( = -132.64 \) kJ/kg
- During constant volume process (2→3), \( W_{2-3} = 0 \)
- **Total Work**: \( W = -132.64 \) kJ/kg
---
### **Step 5: T-v Diagram Sketch**
- Mark points:
- 1: (v1 = 1.5490, T1 = 300°C, P1 = 200 kPa)
- 2: (v2 = 0.88578, T2 = 120.23°C, P2 = 200 kPa, x2 = 1)
- 3: (v3 = 0.88578, T3 ≈ 40.4°C [from interpolation], P3 = 50 kPa, x3 ≈ 0.0698)
---
## **Summary Table for Process:**
| State | P (kPa) | T (°C) | v (m³/kg) | x | u (kJ/kg) |
|-------|---------|--------|-----------|-------|-----------|
| 1 | 200 | 300 | 1.5490 | -- | 2725.5 |
| 2 | 200 | 120.23 | 0.88578 | 1 | 2506.5 |
| 3 | 50 | ~40.4 | 0.88578 | 0.0698| 375.15 |
---
### **Final Answers**
- **Change in Internal Energy (\( \Delta u \)):** **-2350.4 kJ/kg**
- **Work Done:** **-132.64 kJ/kg**
- **T-v Diagram:** (Sketch with points 1, 2, 3 as calculated above)
---
**References:**
- Steam Tables (Water and Steam Properties)
- Refrigerant Tables (R-134a, R-22, NH3, CO2)
If you need the T-v diagram sketch or detailed steps for any other part, let me know!
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