Alfa Laval Launches Hukka-5 Boiler at SMM 2026

Alfa Laval has released the Hukka-5, a next-generation exhaust gas steam boiler engineered for waste heat recovery on cruise vessels and passenger ferries. This thermal management solution utilizes inverted, downward natural circulation to optimize energy capture from four-stroke engine exhaust gases.

Inverted Downward Natural Circulation Technology
Introduced at the SMM 2026 exhibition (September 1–4 in Hamburg, Germany), the Hukka-5 boiler replaces conventional forced circulation mechanisms with an inverted, downward natural circulation design. Natural circulation relies on thermodynamic principles—specifically the density differential between heated and unheated water—to drive fluid movement, eliminating the mechanical reliance on external circulation pumps. Alfa Laval advances this standard by orienting the flow downwards to establish counter-current heat exchange conditions. This configuration maximizes thermal transfer within the spatial constraints of a ship funnel, significantly reducing the physical footprint of the exhaust gas boiler (EGB). Furthermore, the downward flow geometry stabilizes the evaporative circuits, preventing flow instabilities caused by the exhaust gas temperature fluctuations frequently observed when engines run on alternative marine fuels like methanol or hydrogen.

Modular Configuration and Electrical Integration
Designed specifically for the operational profiles of cruise ships and ferries, the Hukka-5 system incorporates modular architecture to allow customizable, multi-stage heat recovery. Operators can integrate an optional condensing cold-end design to further augment the total thermal energy extracted from the exhaust stream. The boiler also standardizes a vertical steam drum, removing installation orientation dependencies. For vessels making frequent port calls, the Hukka-5 enables direct integration of electrical steam generation components without requiring auxiliary fired boilers or additional pressure vessels. This permits the system to produce steam emissions-free when connected to shore power at berth.

Environmental Compliance and Thermal Efficiency
By capturing exhaust heat that would otherwise be lost to the atmosphere, the boiler minimizes the required fuel consumption of auxiliary fired heating systems, leading to a proportional reduction in overall CO₂ emissions.

“Our previous waste heat recovery boiler, Aalborg XWi, set the standard for natural circulation on cruise vessels,” stated Matti Takasuo, General Manager for Business Development and Sales for the Power, Offshore and Cruise business line at Alfa Laval. “Since every square meter matters on cruise ships, the inverted natural circulation design recovers waste heat without increasing the footprint.”

The Hukka-5, part of the broader Hukka product line that includes the Hukka-8, joins an installed base of over 1,300 Alfa Laval marine waste heat recovery systems completed since 2000. These marine and land-based installations collectively mitigate over 10 million tons of CO₂ emissions annually.

Additional Context:
This section details technical specifications and competitive benchmarking not included in the original product announcement

In the marine exhaust gas heat exchanger market, operators evaluate boilers based on thermal efficiency, physical footprint, and system reliability. Competitors such as Kangrim Heavy Industries, SAACKE GmbH, and Miura Co. Ltd. provide both forced and natural circulation economizers. Forced circulation boilers require electrical circulation pumps, which consume supplementary power and introduce the risk of cavitation or soot fires if pump failure occurs during sudden engine load changes. Standard natural circulation boilers eliminate these mechanical failure points by using thermosiphonic flow, but they traditionally require a larger vertical installation envelope. The Hukka-5 distinguishes itself from conventional natural circulation benchmarks by utilizing an inverted downward flow to achieve counter-current heat exchange. This specific geometry allows the unit to compress the heat transfer surface area, delivering the pump-free reliability of natural circulation while meeting the strict spatial constraints required in modern passenger vessel funnels.

Edited by Natania Lyngdoh, Induportals editor, assisted by AI.

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