Page 29 - Climate Control News Magazine June-July 2020

Heat Exchangers
Rotex heat
exchange technology
TRADITIONALLY, A SINGLE DIRECT ENERGY SOURCE HAS BEEN USED TO HEAT WATER.
FOR EXAMPLE A burner flame trans- ferring heat via a combustion cham- ber, or a submerged heating element that has a radiant heat transfer capa- bility into a body of stored water.
The Rotex system, through the use of 316 stainless steel coil heat transfer, provides safe and hygienic hot water in an efficient, reliable and durable manner.
By capturing heat and transferring via a single or series of coils, no sediment remains in situ within the tank. Any impurities from the mains supply are simply flushed out via direct connec- tion to the inner coil surface.
Waste heat can also be used in the form of tak- ing usable heat from a mechanical plant that cre- ates heat in operation. For example, an air condi- tioning system using a super de-heater plate heat exchanger, which acts as a transfer point and with water reticulated through the heat ex- change the ensuing energy can be gained, then stored into the thermal storage tank.
Roof space for solar panels or collectors is an option for new and existing buildings which can exchange heat from solar thermal water or liquid as a direct power energy source and provides a current into heating elements.
Solar PV panels that can be directly connected into vertical heating elements that are used in
INSET: Use the Rotex tank to make use of all the energy in your building.
Rotex tanks can provide a DC supply input and therefore remove the need for an inverter to change the power supply to AC.
Being able to directly inject power via a solar PV field, the DC current takes Off-Grid energy yield to the next level of thermal heat transfer, providing a complete independent energy cap- ture, transfer and provision.
Air that can be exchanged via a compressor in
new commercial heat pumps is also becoming a popular method of delivering DHW instead of gas being used as the energy source.
The Rotex system not only has a small foot- print, it allows a multitude of heat sources to de- liver energy to the storage water which acts as a thermal battery (minimal heat losses of 1.4kW of heat energy over 24 hours). Contact Thermal Energy Solutions for a specific design solution.
Researchers increase speed of cycling heat
Tsinghua University, Beijing
RESEARCHERS FROM TSINGHUA Univer- sity in China and Brown University in the United States have discovered a simple way to give a major boost to turbulent heat exchange, a method of heat transport widely used in heating, ventilation and air conditioning (HVAC) systems.
In a paper published in Nature Communica- tions, the researchers show that adding a readily available organic solvent to common water- based turbulent heat exchange systems can boost their capacity to move heat by 500%.
In 2015, Professor Chao Sun had the idea to use an organic component known as hydrofluor-
oether or HFE to speed the cycling of heat inside this kind of exchanger.
The team showed that concentrations of around 1% HFE created dramatic heat flux en- hancements up to 500%.
The researchers pointed out that the specific additive they used – HFE7000 – is non-corrosive, non-flammable and ozone friendly.
One limitation is that the approach only works on vertical heat exchange systems – ones that move heat from a lower plate to an upper one. It doesn't currently work on side-to-side systems, though the researchers are considering ways to adapt the tech- nique. Still, vertical exchangers are widely used, ✺
CLIMATE CONTROL NEWS JUNE-JULY 2020
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