Air conditioning of ships
Steam -powered fans have been used in shipping since around 1820 , initially as boiler fans and later for room ventilation. With the introduction of passenger ships , luxury was gradually increased; after the invention of refrigeration machines , the air was also cooled and, after 1906, even humidified and dehumidified.
introduction
Regardless of the type of ship, the air conditioning and ventilation conditions on seagoing vessels have a lasting influence on the well-being of the crew, the perceived comfort of passengers and the trouble-free operation of machines, systems and facilities.
Regulations
Ships flying the German flag are subject to the provisions of one of the recognized classification societies , the professional association for transport and traffic management (BG-Verkehr) and the Federal Maritime and Hydrographic Agency (BSH).
Air conditioning / ventilation systems must be designed as self-sufficient systems within the fire zones or watertight departments.
Construction of ship air conditioning systems
The core component of every air conditioning system is the central device in which the supply air parameters are treated and set. Nowadays, almost only modularly constructed units are used on new European ships. it consists of
- Mixing chamber, here fresh air and return air are mixed. 100% fresh air and no circulating air is used for the crew (regulations)
- Filters for air cleaning of dirt and dust
- Preheaters , winter operation, heating media can be hot water (temperature 80–90 ° C), thermal oil, steam or electric heating elements
- Air cooler / air dehumidifier : The filtered air enters the air cooler, cooling to temperatures of approx. 12-14 ° C. Here one finds dehumidification instead. The condensate is collected under the cooler and fed to the ship's drainage system.
With the air cooler, a distinction is made between the direct and indirect cooling process.
- Direct: the refrigerant evaporates directly in the air cooler ( cargo ships ).
- Indirect: Cold water is fed to the cooler with an inlet temperature of 6–7 ° C. Cooling of the cold water in the evaporator ( ferry , cruise ship)
- Humidifier : The air after the preheater has a relative humidity of approx. 20–30%, enrichment with steam or spray humidification to 50–60% is necessary. For reasons of hygiene, steam humidification is preferred
- Water separator: This separates water droplets entrained by the air cooler or from the air humidification.
- Post-heating only in cooling mode
- Fan: The mainly radial type fan is the only moving part of the air conditioner. Drive by an electric motor (mostly frequency-controlled or pole-changing)
- Distribution chamber: The air flow leaving the fan is fed to the individual supply air ducts (number depending on the size of the ship) in the distribution chamber.
In addition to the standard components mentioned above, options are also available if required:
- Activated charcoal filter , if there is a strong odor in the supply air flow, activated charcoal filters can be installed in front of the air cooler / heater combination.
- Heat recovery: To save energy, some heat recovery systems are installed ( regenerator , heat wheel ).
One or two-channel systems
One-channel system with electrical post-heating and heat recovery
An air duct is led from the central air conditioning unit to the air outlet openings in the rooms. This means that all the necessary air treatment (filtering, air cooling / heating, humidification) occurs in the central device. The volume flow is regulated in the outlet devices in the cabins and electrical reheating can take place. This means that every room receives a variable volume flow and, within narrow limits, readjustment of the temperature.
The exhaust air is sucked in from the cabins via the corridors (and stairwells) and mixed with the freshly supplied air as recirculated air. The exhaust air from the sanitary and kitchen areas is discharged separately and to the outside.
Two-channel system with circulating air
Two separate air lines (one each for cold and warm air) supply the rooms. The basic conditioning takes place in the central device. The warm air flow experiences an additional temperature increase through a reheater and the cold air flow flows directly to the outlet devices. Warm and cold air flows are then mixed in the outlet device.
Air conditioning systems on passenger and ferry ships
Passenger and ferry ships have a higher degree of comfort compared to merchant ships . This requires a greater degree of technical effort, particularly in terms of system control. In principle, the systems used on merchant ships are also available. As a result of the disadvantages of the one- and two-channel systems, a third variant, the fan-coil system , has been developed in recent years for the construction of large cruise ships .
Fan coil system This type of system is based on the principle of decentralizing air conditioning. In the climatic room, preconditioning (filtering, air cooling / heating, humidification) is carried out using significantly smaller central devices. This air enters the rooms via a one-channel system. Instead of the usual outlet devices, each room has a fan coil device that can locally heat and cool the air. This consists of a filter for secondary air, an air cooler with a control valve , an electrical reheater and a fan (at least 3-stage). The fan coil units are installed either upright in / on the wet cell or horizontally in the cabin ceiling and have a condensate and cold water connection. The primary air coming from the ducts is mixed in either on the pressure or on the suction side.
Air conditioners with direct cooling
Air conditioning systems for cargo ships usually work with direct cooling, ie the evaporator is located directly in the central air conditioning unit. The liquid chillers for ship operation consist of a compact unit with the following components: Compressor , evaporator, oil cooler , pipes and fittings, an attached or separate switchgear with all control functions and attached or separate cooling water and brine pumps. This type of construction can be deviated from, especially for ship operations, in order to be able to use z. B. to set up the capacitor separately.
Air conditioning systems with indirect cooling
In the case of air conditioning systems over approx. 400 kW and several branched air conditioning units or when using absorption refrigeration systems , the use of central liquid chillers is recommended. Water with a flow temperature of approx. +6 ° C is usually selected as the coolant to supply the air conditioning cooling units.
At temperatures below +5 ° C or if the cold water pipes are laid in a frost area, the pipes are protected against freezing. For this purpose, glycol is used at temperatures up to a frost protection of - 20 ° C, at lower temperatures special cooling brines are used. However, this does not play a practical role in the air conditioning cooling sector.
Mechanical compressors
Piston compressors , screw compressors and turbo compressors are used as compressors .
- Piston compressors are used for small capacities (cargo ships).
- Screw compressors are available from an output of approx. 50 kW up to an output of 4.5 MW, and are mainly used for medium power requirements (ferries, passenger ships).
- Turbo compressors are used for large and large outputs (large passenger ships). Magnetic bearing turbo compressors are still quite new and have good market opportunities.
Cold water network
A series connection of the evaporators with a common pump, a parallel connection of the evaporators with a common pump or a parallel connection of the evaporators with individual pumps can be used to set up the cold water network. For machine control rooms as well as for the subsequent air conditioning of individual rooms, such as B. trade fairs, salons, etc., complete, ready-to-connect climatic cabinets are used.
Absorption chiller
In compression refrigeration systems , the energy is supplied in the form of mechanical energy in the refrigerant compressor. In the absorption refrigeration system , on the other hand, energy is supplied by thermal energy (steam from the exhaust gas boiler, hot cooling water) in the cooker.
In addition to the refrigerant, an absorbent is required that has the ability to suck up the refrigerant vapor (to absorb it, working substance pairs). This happens in an additional component, the absorber.
Compared to compressor refrigeration systems, absorption refrigeration systems consume more energy and are therefore less efficient. This is not a disadvantage if the waste heat is available free of charge. If the waste heat can be used over short distances, as is particularly the case on the ship, a lot of primary energy and thus carbon dioxide (CO 2 ) can be saved.
The working substance pair lithium bromide / water is used for air conditioning (the working substance pair water / ammonia is used for low temperatures). The advantages are the noiseless operation and the long service life, since the units apart from centrifugal pumps contain no mechanically moving parts and therefore practically no wear parts. However, a prerequisite for trouble-free operation is very careful processing during welding, flushing and filling of the units so that sludge formation and blockages in the pipeline system do not occur.
literature
- G. Drews: Ship ventilation and warm air heating. In: Handbook of the shipyards. Volume 9, Schiffahrtsverlag Hansa.
- V. Behrens, K.-H. Hochhaus, Y. Wild: Ship ventilation and air conditioning. In: Handbook of the shipyards. Volume 25, Schiffahrtsverlag Hansa, pp. 49–114.
- R. Wille: Ventilation systems for ships. In: Yearbook of the Shipbuilding Society 1953. Springer Verlag, Hamburg.
- International convention of 1974 for the protection of human life at sea, amended by the protocol of 1988 (SOLAS 74/88) in ship safety regulations, Seeberufsgenossenschaft 1995.
- Revision of the GL guidelines for ventilation systems on board seagoing ships, Germanischer Lloyd, draft as of November 3, 1999.