Objective
To incorporate solar technology and energy saving equipment in a factory complex, primarily to meet air conditioning and heating requirement but also for architectural and cost saving purposes.
An immediate economic return is not the prime objective of this project since it is very much dependent on shifts in the price of conventional energy sources. It cost Pernod 12% more to construct this solar plant than if only electric heating were used, and 10% more than one utilizing LPG. The specially designed insulation will itself enable more heat to be saved.
By using solar energy and heat recovery systems, up to 50% of the plant's heating and hot water requirements are saved, or in other words +/- 195 TOE/y.
Initially, problems were encountered with collector components, particularly the foundry manufactured fitting joints and with the collector flexible seals (to provide a tight fit and expansion) and with mounting of the assembly (one collector is 16 m in height and subject to - 10 deg.C to + 140 deg.C temperature variation).
With the assembly mounting, expansion was the main problem which contributed to loss of static and/or dynamic air. It also became apparent that the static air thin layer should not be totally isolated, but should be allowed to 'breathe' (although this does not amount to permanent air renewal). The exhaust of vapor from the static thin layer (linked to the breathing effect was also observed). Due to production problems, the glazed sheet steel plates tended to oxidize where pinched during the enamel coating process.
In purely technological terms, and in spite of a longer than anticipated start-up, the system is functioning more closely to design specifications (due to corrections worked into the system). Temperatures of 60 deg.C have been reached at collector outlet and in excess of 40 deg.C in the thermal storage.
It is also recommended for future plant design, that the following points be taken into account :
- digital techniques should be used for process control, not the orginally specified analogue methods;
- air and not water collectors should be used, but future fitting standards should be for water-tightness;
- only components with a proven performance should be chosen, and in particular components with a useful working life expectancy in excess of the usual contractor's guarantees;
- schedules for component and plant maintenance should be worked out at the design stage;
- it is also important to bear in mind the matter of collector interchangeability by constructing collector walls which may be dismantled;
- where there is access to the facilities, doorways etc., tight, power assisted controls should be in operation to ensure proper closing;
- access to high temperature zones must be protected by 'specially adapted safety devices';
- since the system operates on low energy levels, it is important to remember that it is easily set-off by controls defects, and therefore requires total automatic, and independent control, equipped with sensors at each terminal;
- managerial and staff training should take account of the new technologies being used;
- the system should be intelligible to users.
The Pernod Solaire plant comprises three separate buildings, each with different heating characteristics. Air conditioning and heating are derived from two principle energy sources : solar energy and electric power.
Independently programmable automatic control units are sited in each building and may be controlled by a central microprocessor. In some buildings, recovery processes such as those provided by heat exchangers and heat pumps are also used to provide an additional energy source.
The system is comprised of :
- a solar energy collecting system consisting of air collectors and capable of supplying 27% of total heating requirements;
- a low temperature energy storage derived from electrical power;
- a high temperature energy storage derived from elecical power;
- a system to utilize electric power (providing up to 47% of total energy requirements) consisting of either a PAC (packaged assembly circuit) or batteries operating either through accumulation or direct connection.
These four heat sources, working in hierarchical programme, transfer their heat to the air flow, providing for both air renewal and building heat. The criteria for calling on any of these sources depends on its availibility, cost and the prevailing energy requirement. In descending order of priority, the following sources may be called upon :
- the heat loss recovery process
- solar energy
- the heat pump
- electric power in deferred mode
- mains power (in emergencies)
The solar energy system is comprised of :
- collectors
- greenhouses
- solar and electric energy storage
- heat pumps
- control devices
Incident solar energy is collected by high temperature baked enamel panels capable of withstanding 130 deg.C temperatures. An insulating coat is applied to the rear face. For reasons of cost the collectors are incorporated into the building's walls. These 'composite walls' have a three-fold function: sealing, solar energy collection and thermal insulation. They also render unnecessary the need for a collector supporting framework and for jackets for unit collectors. Neither is there any need for the connecting bridges normally required when a mosaic of unit collectors is used.
Five greenhouses are situated for optimal exposure (South-East & South West). In the context of this report their most important function (out of three) is preheat air before it circulates in the collectors.
Solar energy storage is located in the basement of all three buildings. For several reasons (eg. to eliminate air/water exchangers which would lead to loss of ouput) a solid solar energy storage medium was chosen over water. The result of tests was a new component called Heliobloc, derived from a concrete building block through which multiple air channels are drilled. During operation, Heliobloc temperature may reach +/- 60 deg.C and is capable of withstanding 150 deg.C maximum. Refractory bricks capable of operating at + 650 deg.C are used for electric heat storage: electric resistance heating.
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DEM - Demonstration contractsCoordinator
94015 Creteil
France