Solar heating offers big energy savings
July 24th 2008 A tried and proven evacuated tube solar collector linked to boilers and plate heat exchangers saves money by maximising the energy efficiency of heating systems while also minimising heat loss through radiation.
The ultra high efficiency Ecotube, developed and patented by Riomay and now available from Stokvis Energy Systems, radically reduces the amount of 'parasitic' energy (energy used up by the system itself when converting solar energy to heat) lost by most evacuated tube solar heating systems.
As a result, the system requires smaller pumps to circulate the fluid in the evacuated tube collector. This means that there are fewer drops in pressure through the system, giving a more sustained level of heat than most other systems.
Independent laboratory tests prove that the Ecotube produces more than 750kWh/m2 per year in direct heating mode and a staggering 850kWh/m2 per year in pre-heat mode.
The system is an advanced form of evacuated tube collector that absorbs solar radiation and uses that energy to raise the initial temperature of a hot water system. The energy absorber is simply a strip of aluminium treated with an advanced selective Tinox coating and bonded to a concentric copper pipe through which fluid is passed to collect the heat. The whole assembly is sealed within an evacuated glass tube and the vacuum that is produced virtually eliminates heat losses by convection or conduction.
Ecotube has a higher performance than flat plate systems and competing evacuated tube systems because it benefits from the use of:
High transmittance glass that is virtually transparent to solar energy.
A super-efficient selective coating on the absorber plate that maximises the solar energy absorbed and minimises the heat energy lost by radiation.
A highly durable glass-to-metal seal at the end of each tube to maintain the high vacuum that prevents energy losses by convection and conduction.
Glass and metal components that expand and contract at the same rate in response to temperature changes, resulting in a reliable system whatever the season.
A unique concentric pipe direct flow design that increases siting flexibility by allowing the panel to be placed in any orientation.
Because of their sophisticated vacuum tube design, Ecotube panels are air temperature independent, so they work extremely well on cold, clear, frosty days. The indirect system eliminates problems caused by the build-up of limescale and also ensures that the system cannot freeze in winter. Automatic sensors prevent energy losses at night and during the darkest days of winter, and the use of a special heat transfer fluid eliminates any risk of freezing.
Ecotube provides siting flexibility since it can be installed flat on a roof, at an angle or horizontally on flank walls.
For facilities managers, Stokvis-Riomay solar heating systems reduce the cost of heating water for changing rooms, laundries, kitchens, swimming pools, baths and showers.
Stokvis-Riomay Ecotube is versatile enough to be used in a wide range of applications, including:
Housing associations: Solar water heating is an attractive option for housing associations thanks partly to Government grants that can cover half the investment cost.
Schools: Stokvis-Riomay systems can heat school swimming pools and provide hot water for use throughout the school premises, summer and winter.
Businesses: Stokvis-Riomay is the ideal way to help businesses achieve their green energy goals and to mark them out as environmentally enlightened companies. Investing in solar energy is also cost effective for businesses since financial help is provided by government grants or Enhanced Capital Allowance tax relief.
Seasonal businesses: Solar thermal heating is ideal for seasonal businesses such as hotels, bed-and-breakfast establishments and caravan parks, where the demand for constant hot water peaks in the summer. The cost of providing the hot water required by en-suite bathrooms, shower blocks and laundries can be prohibitive, particularly for smaller businesses and those that operate for only a few months each year; Ecotube solves this problem at a stroke.
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