A water to water heat exchanger is an efficient, powerful and very compact way to heat cold water from a hot water source without the two streams of water mixing. It operates via principles of convection. Convection which occurs when heat transfers between hot and cold liquid, heating the cold liquid and cooling the hot liquid. Common applications are in HVAC systems, domestic water heating, solar heating and car radiators.
Why would I use a heat exchanger?
In situations where heat exchange is required to take place, one stream of water may contain contaminants or chemicals that can’t be mixed with the water to be consumed such as a hot water system powered by solar energy. The tubes of the solar water heater contain descaling solution to maintain efficiency in the system. The heated water from the solar water heater is run through a heat exchanger, heating the water for domestic use without passing on the contamination.
Plate heat exchangers are a favourite design as they are compact and lightweight and can also be easily expanded and enlarged if the requirement for a larger system becomes necessary.
How are plate heat exchangers made?
Plate heat exchangers are constructed from a series of plates with matching holes that are stacked together and sealed. The plates are constructed from stainless steel and copper which is a powerful conductor of heat thanks to its chemical composition. The parallel plates are arranged in an alternating pattern to create a counter flow of liquid. Patterns in the plate direct the liquid to travel through troughs which are formed at right angles to the direction of the liquid flow.
How is heat transferred?
Hot and cold water is piped through the plate heat exchange, creating a stream of water in each direction. The hot liquid enters from the top and exits from the bottom and the cold liquid does the opposite. As the separated hot and cold water flow past each other, the metal absorbs the temperature from one stream of water and transfers it to the other.
More about heat exchangers
Both streams of water are piped into the same end of the heat exchange in most installations. This allows more plates to be simply added to the opposite side when expansion is required. Often the pipes holding the heat exchange in place will be extended beyond its actual size for this reason.
Water to water heat exchanges are measured in flow rate (litres per hour), thermal energy capacity (Kw) which is how much thermal energy it can supply, and transmission area (m2) which is the area of all the plates if they were laid side by side.
Plate heat exchangers offer a very efficient method of water to water heat exchange and are a favourite in industrial and domestic use. To find out more about the size and type of water to water heat exchanger for your project, consult the experts at RSOnline.
