Nguồn gốc:
Trung Quốc
Hàng hiệu:
Yuhong
Chứng nhận:
TEMA ASME VIII-1
Số mô hình:
bộ trao đổi nhiệt kẹp tóc
| Parameter | Hairpin Heat Exchanger | Conventional Straight Shell-and-Tube (1-2 Pass or U-Tube) | Parameter-Based Justification |
|---|---|---|---|
| Flow arrangement | True countercurrent (single pass both sides) | Mixed / cross-countercurrent (F factor < 1.0 for 1-2 or 2-4 pass) | Hairpin LMTD correction factor F = 1.0 per TEMA. For 1-2 shell-and-tube, F ≥ 0.8 required; below 0.8 requires multiple shells in series. |
| Thermal approach (hot outlet vs cold inlet) | Achievable approach ΔT = 3°C to 5°C | Achievable approach ΔT = 10°C to 15°C (single unit) | Hairpin F=1.0 allows approach limited only by NTU. For shell-and-tube with F=0.85, required NTU increases by 18% for same approach. |
| Differential thermal expansion (tube vs shell) | Accommodated inherently by U-bundle free end | Fixed tube sheet requires expansion joint when ΔT > 60°C (CS/CS) or > 40°C (CS/SS) | Per TEMA RCB-4.3: fixed tubesheet without expansion joint limited to differential expansion stress ≤ 55 MPa. Hairpin has no such limit below material creep range. |
| Maximum ΔT (tube side to shell side inlet) | Up to 200°C (within ASME VIII-1 stress allowables) | ≤ 60°C (carbon steel fixed tubesheet without expansion joint) | Based on thermal stress calculation per ASME VIII-1 UG-23(c): for CS with E=200 GPa, α=12×10⁻⁶ /°C, ΔT=200°C yields σ=α×E×ΔT/2 = 240 MPa - exceeds 138 MPa allowable. Hairpin avoids this by free-end U-bundle. |
| Single-unit surface area range | 1 m² to 500 m² (multitube) | 5 m² to 2,500 m² | Hairpin limited by bundle pull-through weight (max bundle mass ~10,000 kg for vertical pull). Straight-shell limited by shell diameter (typically ≤ 2.5m ID) and transport limits. |
| Shell-side pressure drop (single pass) | ΔP = f × (L/D_h) × (ρv²/2) with L = total hairpin developed length (2× straight leg + return bend) | ΔP per TEMA for E-shell (single pass shell) | For identical duty and shell-side mass velocity, hairpin pressure drop is approximately 40-60% higher than straight E-shell due to return bend losses (experimental correlation from HTRI). |
| Mechanical cleaning access (shell side) | Limited - return bend housing restricts access | Full access for floating head or pull-through bundle (U-tube) | Hairpin shell side cannot accommodate a pull-through bundle. Fixed bundle requires chemical cleaning. Shell-side fouling factor > 0.0005 m²*K/W is not recommended for hairpin without chemical cleaning capability. |
| Tube-side cleaning (mechanical) | Full access - U-bend radius ≥ 2× OD allows standard tube wiper | U-tube: accessible (same bend radius rule). Fixed tubesheet: full access. | Per TEMA RCB-4.52: minimum U-bend radius = 2× tube OD for mechanical cleaning. Both designs comply. |
| Footprint (installed length for equivalent duty) | Straight leg length L (2L total developed length but stacked or side-by-side) | Straight length L_shell (usually 1.2× to 1.5× hairpin leg length for same surface area) | Hairpin multitube typically requires 40-50% less linear space because surface area is distributed over two legs in parallel. Actual layout dependent on headroom and tube count. |
| Typical maximum design pressure (tube side) | Up to 35 MPa (single tube hairpin / double pipe) | Up to 20 MPa (multitube bundle with welded tubesheet) | Per ASME VIII-1 and VIII-2: seamless tube in double-pipe hairpin eliminates tubesheet ligament stress concentration. Multitube bundle limited by tubesheet hole deformation (ASME VIII-1 UG-34). |
| Standard manufacturing code | TEMA C / B / R + ASME VIII-1 or VIII-2 | TEMA C / B / R + ASME VIII-1 | Both designs follow same TEMA and ASME sections. Hairpin return bend cover requires additional UW-13 weld detail. |
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