Shell-and-tube Evaporator

The Shell-and-Tube Evaporator is the preferred evaporator type for systems above 50 kW cooling capacity, where its high thermal mass, tolerance for dirty or corrosive process fluids, and ease of mechanical maintenance give it decisive advantages over plate, coil, or brazed-plate alternatives. Lynxcool engineers and manufactures each Shell-and-Tube Evaporator to project-specific thermal and pressure requirements, with design codes covering GB 151, ASME Section VIII Div. 1, and PED 2014/68/EU.

Standard refrigerant compatibility includes ammonia (R717), CO₂ (R744), HFC blends (R22, R404A, R507A, R134a, R410A), and next-generation HFO/HFC blends (R448A, R449A, R452A). Custom material specifications are available for high-pressure CO₂ transcritical circuits and for process fluids outside standard water/glycol chemistry.

Technical Parameters

Application Scope

Industrial Refrigeration

•Cold-storage and refrigerated-warehouse chiller barrels — flooded R717 or R744 circuits

•Blast-freezing and spiral-freezer glycol circuits — low-temperature brine down to -55 °C evaporating

•Ammonia packaged screw chiller units — DX or flooded shell-side configurations

•CO₂ transcritical booster systems — high-pressure gas cooler and evaporator duties

Process & Industrial Cooling

•Chemical reactor jacket cooling — corrosion-resistant titanium or 316L tube bundles

•Plastics injection-moulding and extrusion chilled-water circuits

•Food & beverage fermentation tanks and pasteuriser cooling loops

•Pharmaceutical clean-room process cooling with GMP-compatible surface finishes

•Data-centre glycol loop secondary cooling (high flow-rate, low ΔT designs)

HVAC & District Cooling

•Large centrifugal and screw chiller barrels — replaces OEM components or standalone upgrade

•District-cooling heat-exchanger stations — water-to-water or refrigerant-to-water duties

•Free-cooling hybrid circuits — high-pressure hot-water recovery evaporators

Core Technical Features

1.  Flooded vs. DX Shell-Side Configuration

Lynxcool designs the Shell-and-Tube Evaporator in either flooded or direct-expansion (DX) shell-side configurations. Flooded evaporators maintain a liquid refrigerant level across the full tube bundle, maximising wetted surface area and delivering overall heat-transfer coefficients (U) 20 – 35 % higher than DX at the same tube geometry. They are the standard choice for ammonia systems and large HFC screw chillers. DX configurations are applied where liquid-charge minimisation is critical — CO₂ safety zones, HFO low-GWP systems, or modular chillers where refrigerant inventory control is a regulatory requirement.

2.  Enhanced Tube Surface Geometry

Standard copper tubes are specified with an internally grooved (micro-fin) profile on the water/process side, increasing the internal wetted area by 60 – 80 % versus a smooth bore and inducing turbulence at lower Reynolds numbers. The refrigerant-side external surface uses a low-fin profile (26 fpi) that increases nucleate boiling area and reduces the onset of dry-out. For ammonia flooded applications, smooth external tubes are used to avoid liquid entrainment — the larger bubble departure diameter of NH₃ benefits from an unobstructed external surface.

3.  Multi-Pass Tube Arrangement

Single-pass designs minimise pressure drop in high-flow, low-ΔT applications (data-centre cooling, district cooling). Two-pass and four-pass designs increase tube-side velocity at lower flow rates, maintaining turbulent flow (Re > 10,000) and high film coefficients even at part load. The pass configuration is selected during thermal design to meet project-specific ΔT, pressure-drop, and pump energy targets simultaneously.

4.  Pressure Vessel Engineering & Code Compliance

Every Shell-and-Tube Evaporator shell is fabricated from certified pressure-vessel plate (Q345R or SA-516 Gr.70), radiographically tested at longitudinal seams (RT Grade II), and hydrostatically proof-tested at 1.25× design pressure before insulation. Tube-to-tubesheet joints are roller-expanded and seal-welded for ammonia service. Third-party inspection by CCS, TÜV, or Bureau Veritas is available on request. Full Material Test Reports (MTRs), weld maps, and pressure-test certificates are supplied with every unit.

5.  Corrosion Protection & Material Flexibility

Shell-side corrosion protection is inherent in the refrigerant fluid environment. Tube-side material is selected to match the process fluid: standard TP2 copper for clean chilled water; 316L stainless steel for mild acids, chlorinated water, or food-grade circuits; titanium Grade 2 for seawater, brackish water, or aggressive chemical duty; cupronickel 90/10 for marine applications. Tube-sheet material is matched to the tube alloy to eliminate galvanic coupling.

6.  Factory Assembly & Testing

Each Shell-and-Tube Evaporator is fully assembled, insulated, and pressure-tested at the Lynxcool factory before shipment. Connection flanges are match-drilled to customer piping specifications. Factory-applied closed-cell polyurethane insulation (50 mm standard, 75 mm for low-temperature duty below -20 °C evaporating) eliminates on-site insulation labour and ensures consistent moisture-barrier integrity. Units are shipped with nitrogen holding charge (0.05 – 0.1 MPa) to prevent internal oxidation during transit and storage.

Why Partner with Lynxcool

•Project-specific thermal design: every Shell-and-Tube Evaporator is sized to your exact load, fluid properties, fouling factors, and allowable pressure drop — not selected from a fixed catalogue

•Multi-code fabrication capability: GB 151, ASME VIII Div. 1, and PED 2014/68/EU from a single factory, reducing the number of vendors on international projects

•Full refrigerant compatibility: ammonia, CO₂ transcritical, HFC, and next-generation HFO blends all supported with appropriate material and sealing specifications

•Documented quality package: MTRs, radiographic test reports, hydrostatic test certificates, and nameplate data supplied as standard — no additional charge

•Integrated insulation and coating: factory-finished units arrive ready to connect, eliminating field insulation subcontracts and QA gaps

•Replacement and retrofit expertise: Lynxcool can re-engineer a drop-in replacement for any OEM chiller barrel, matching flange pattern, shell footprint, and nozzle orientation to minimise plant downtime during changeout

•China-manufactured cost advantage: 25 – 40 % below equivalent European pressure-vessel manufacturers at comparable certified quality levels, with ASME U-stamp and PED CE-marking available

Frequently Asked Questions

Q: What is the difference between a flooded and a DX shell-and-tube evaporator?

A: In a flooded evaporator, the shell contains a pool of liquid refrigerant that submerges the entire tube bundle; refrigerant boils from the liquid surface upward, maximising wetted area and heat-transfer coefficients. In a DX (direct-expansion) evaporator, the expansion valve meters refrigerant into the shell inlet and the refrigerant is fully evaporated before reaching the outlet; liquid charge is significantly lower. Flooded designs achieve 20–35 % better U-values and are preferred for ammonia and large HFC systems. DX designs are chosen when minimising refrigerant inventory is a priority.

Q: Which tube material should I specify for my process fluid?

A: For clean chilled water or glycol, standard TP2 copper is the most cost-effective choice. For mild acids, chlorinated cooling-tower water, or food-contact circuits, specify 316L stainless steel. For seawater, brackish water, or aggressive chemical duty, titanium Grade 2 provides the best corrosion resistance. Lynxcool's thermal engineers will confirm material compatibility against your fluid chemistry report before issuing the fabrication drawing.

Q: Can you manufacture a replacement barrel for an existing chiller brand?

A: Yes — this is one of our most common project types. Provide the OEM nameplate data, connection flange drawing, and shell footprint dimensions, and Lynxcool will engineer a drop-in replacement that matches the original thermal duty and all mechanical interfaces. Retrofit units are typically delivered in 8 – 12 weeks and installation is a direct swap, minimising plant downtime.

Q: What fouling factors do you use in thermal design?

A: Default fouling factors follow TEMA standards: 0.000088 m²·K/W (0.0005 hr·ft²·°F/BTU) for clean chilled water tube side and 0.000176 m²·K/W (0.001) for cooling-tower condenser water. Customers may specify project-specific fouling allowances; we incorporate them directly into the HTRI or Bell-Delaware thermal model and document them on the datasheet.

Q: What is the maximum operating pressure for CO₂ transcritical service?

A: For CO₂ high-pressure (gas-cooler) side, Lynxcool designs to 12 MPa design pressure using SA-516 Gr.70 shell plate and high-pressure carbon-steel or stainless-steel tubes, fabricated per ASME VIII Div. 1. For the low-pressure evaporator side of a CO₂ booster system, standard 4.0 MPa design is typically sufficient. Both are within the factory's current code scope.

Q: How is the Shell-and-Tube Evaporator insulated, and can the insulation be removed for maintenance?

A: Factory-applied 50 mm closed-cell polyurethane foam (75 mm for sub -20 °C duty) is bonded to the shell exterior and finished with a glass-fibre reinforced jacket. Both end bonnets (water boxes) are left un-insulated or fitted with removable insulation pads, allowing tube-bundle access for mechanical cleaning or tube inspection without demolishing the main insulation. Tube plugging or bundle replacement can be performed on-site without refrigerant recovery from the shell side if the unit is isolated and drained.

Q: What lead time and documentation package should we expect?

A: Standard units (DN 200 – DN 800, copper tubes, GB 151 code): 4 – 6 weeks from drawing approval. Large or special-material units (DN 1,000+, titanium, ASME U-stamp, PED): 8 – 14 weeks. Standard documentation package: General Arrangement drawing, thermal datasheet, material test reports, weld map, radiographic test report, hydrostatic test certificate, nameplate rubbing, and packing list. Third-party inspection certificates (TÜV, BV, CCS) are included when specified at order.