Cooling apparatus The invention relates to a cooling apparatus suitable for cooling water, for example, the cooling water of a marine engine, comprising cooling pipes through which the cooling water is conducted, a pipe plate on which the cooling pipes are mounted, and a water header at the side of the pipe plate facing away from the cooling pipes, which water header has connecting stubs for inlet and out- let of the cooling water.

Such a cooling apparatus has already been in ex- istence for 40 years. A cooling apparatus is a heat ex- changer used on sea-going ships that have 5 to 10 mega- watt-powered marine engines. Such ships have a length of between 30 and 150 metres. As a rule the cooling apparatus is used for cooling the cooling water of the marine en- gines. Of course, the cooling apparatus can also be em- ployed for cooling water from another source. For the pur- pose of cooling, heat exchange takes place between the cooling fluid in the cooling apparatus of the marine en- gine and the surrounding seawater. The cooling apparatus is mounted in a cavity in a special watertight space be- hind the ship's hull. The ship's hull is provided with in- let and outlet openings to allow the seawater access to the cooling apparatus. The pipe plate plays an important role in the cooling apparatus. Said pipe plate has a num- ber of functions, such as -separating the cooling water and the seawater and ab- sorbing the inherent pressure difference; -leak-proof fixing of the cooling pipes; -carrying mechanical stresses on the cooling pipes and transferring these stresses to the ship's hull; -positioning the cooling pipes (subject to the chosen manufacturing process); -distributing the flow of the cooling fluid in the water header;

-stabilizing vibrations in the pipe coil.

The cooling apparatus as such and its parts such as the pipe plate, have to comply with strict require- ments. The desired mechanical life of the cooling appara- tus is 20 years and this also applies to the pipe plate.

This mechanical life corresponds with that of the ship in which the cooling apparatus is installed. Consequently the cooling apparatus is sold as a maintenance-free product.

This means that the occurrence of unforeseen maintenance is not permitted, whereas customary planned maintenance may take place. This takes place when the ship is docked.

The cooling apparatus and the pipe plate have an important safety function. As mentioned above, the cooling apparatus is located behind a cavity in the ship's hull.

This means that the cooling apparatus must be leak-proof at all times, including under conditions of fire and in the presence of corrosive liquids and gases.

One can imagine that the pipe plate of the cool- ing apparatus is subjected to considerable stress. The pipe plate has to be able to withstand all thermomechani- cal stresses; short-term (stationery, blow, impact, vibra- tions), long-term (creep, stress relaxation), thermal stresses and thermal shock. The thermal limits are deter- mined, among other things, by thermal safety measures ap- plied to the marine engine itself.

Due to the extensive requirements the cooling apparatus and the component pipe plate have to meet, the known cooling apparatus is a costly product. The cost price of the known cooler (price level 1999) is from about NLG 2,500 for the smallest model to NLG 40,000 for the larger models.

With all these technical requirements, the fact that the known cooling apparatus and its integral parts such as cooling pipes, pipe plate and water header, are made of metal, is a problem. In the prior art the cooling pipes and pipe plate are substantially made of a copper alloy. This results in the problem that the mounted cool-

ing apparatus causes corrosion problems due to contact po- tentials.

It is the chief objective of the invention to eliminate this corrosion problem and at the same time to provide a cooling apparatus that can be manufactured at lower costs, while continuing to comply with all the re- quirements with which the cooling apparatus is confronted in practice.

In order to serve these purposes, applicant has broken with the many decennias-old practice, and the pres- sure from insurance companies to manufacture the cooling apparatus for safety reasons entirely of metal, and has discovered after a prolonged and costly period of develop- ment, that the aims of the invention may be realized with a cooling apparatus whose pipe plate is made of plastic.

Desirably the plastic has a load-bearing capac- ity of up to 6 bars overpressure at a temperature ranging from-20°C to +100°C. In this way the load requirements oc- curring in practice can be met, while in addition the load-bearing capacity of the plastic pipe plate is main- tained during the entire mechanical life of the cooling apparatus.

In a further advantageous embodiment variation of the cooling apparatus according to the invention, the pipe plate and the water header form a whole. The cost price of the cooling apparatus embodied with the plastic pipe plate is already reduced by approximately 20-30%.

This cost price may be further reduced by means of the measure just mentioned.

It is further advantageous to embody the cooling apparatus such that the same is provided with a substan- tially copper-comprising element which, when the cooler is installed in a ship, can be adjusted to an anodic poten- tial. This is a very simple and effective manner of pro- tecting the cooling apparatus against fouling problems, caused by the growth of organisms.

The invention will now be explained with refer- ence to the drawing of a single Figure 1. Figure 1, shows

as silhouette a ship 1, and in detail a cross section of a cooling apparatus mounted in the ship. It is a ship of the type discussed above, namely with a length between 30 and 150 metres and provided with a 5 to 10 megawatt-powered engine. In the ship's side, approximately in the circle 2, a cooling apparatus 3 is installed. Said cooling apparatus 3 is mounted in a space behind the ship's hull 6, made wa- ter-tight by means of partition plates 4 and 5. Via the openings 7 and 8, the space delimited by the partition plates 4 and 5 and the ship's hull 6, is freely accessible to seawater. The cooling apparatus 3 has connection stumps 9 and 10 for the supply or discharge of cooling water to the marine engine (not shown). Said connection stumps 9 and 10 form part of a water header 11, which is in commu- nication with a pipe plate 12. On the said pipe plate 12 the cooling pipes 13 are mounted, through which flows the cooling water of the marine engine, supplied and dis- charged via the connection stumps 9 and 10. The pipe plate 12 is made of plastic, which preferably has a load-bearing capacity of up to 6 bars in a temperature range from-20°C to +100°C. Due to its plastic embodiment, said pipe plate 12 provides a galvanic separation between the ship 1 on one hand and the coil of cooling pipes 13 on the other hand, thereby safeguarding said cooling pipes against cor- rosion problems.

In an advantageous embodiment variation which will be clear to the person skilled in the art without re- quiring any further explanation, the pipe plate 12 and the water header 11 are designed such as to form a whole. Also not shown but completely clear to the person skilled in the art, is a favourable embodiment variation in which the cooling apparatus 3 is provided with a substantially cop- per-comprising element which, when the cooling apparatus 3 is installed in a ship, can be adjusted to an anodic po- tential. This latter feature effectively combats fouling of the cooling apparatus, thereby ensuring that a high level of cooling power is maintained.