Heating and Cooling
In aquaculture heating of the water may be necessary for several reasons, for example to increase the growth rate, to get the fish reach a specific size at a certain time, to get them to mature or to spawn. Different species have different optimal temperatures; if the ambient water temperature is cooler than the optimal temperature, it can be useful to heat the water.
The principles used for heating in aquaculture are normally the same as those used in houses or industrial facilities; however, systems used in aqua-culture facilities must heat large amounts of water and therefore be efficient. Important factors when choosing a system are the total heating requirements and the necessary temperature increase. In this chapter a survey of methods and equipment is given. It starts with some basic physical laws and ends with some simple specifications and calculated examples.
Instead of purchasing all the heat necessary, it could be taken from other available sources, such as geothermic water, or the water could be re-used. For species needing much warmer water than is avail-able from source, both these methods could be used.
In some cases it is necessary to chill the water, for instance in connection with storing the brood stock, to get the fish to mature, and for storing eggs and fry. Heating and chilling both involve energy transfer. When heating water, energy is added to the system, while chilling removes energy from the system. In this chapter the focus is on heating systems used for aquaculture; much of the basic information applies to both heating and cooling. A great deal of general engineering literature is avail-able on this subject and also on basic thermodynamics; .