MP has recently completed, via its subsidiary SOLARMAC, the installation of two solar heating facilities for the production of Sanitary Hot Water (SHW), in the swimming pools in the neighbourhoods of Bellavista and San Jeronimo, in Seville. These two installations, which were identical in terms of the project and execution, are capable of providing 70% of the swimming pools’ energy needs for supplying hot water to the bathrooms, toilets and changing rooms of these buildings.

These projects have been designed in accordance with the Regulations on Building Heating Installations (RITE), and in accordance with the stipulations of the Energy Saving and Efficiency Plan (of the 1991-2000 National Energy Plan). The approach adopted with these installations has allowed us to combine maximum comfort and economy for the user with maximum energy saving and protection of the environment.

The use of renewable energy to meet energy needs instead of traditional energy sources considerably reduces the emission of contaminating gases into the atmosphere. The data on this type of installation shows that the use of solar heating systems reduces the emission of CO2 into the atmosphere by 38,200 kg. per year and by almost 1,000 tonnes over the entire useful life of the installation.

DESIGN OF THE HEATING INSTALLATION

Each installation is basically composed of 20 MP Solarmac S25S solar collectors. In each swimming pool, a sur face area of 48 m2 has been allocated to solar collection. Moreover, each installation has an accumulator of 4000 L and a 25 plate heat exchanger with 159 kW (137,200 Kcal/hr) of exchange capacity.

The use of solar heating systems reduces the emission of CO2 into the atmosphere by 38,200 kg. per year and by almost 1,000 tonnes over the entire useful life of the installation.

In both projects, the size of the accumulator capacity was calculated on the basis of covering the monthly SHW needs of the building, calculated according to an estimated figure of 200 users per day. The RITE specifies, for this type of installation, a consumption level of approx. 20l per person per day.

The calculation of the area of collection by the solar field was made taking into account the following:

• Energy needs of the installation (200 million kJ/year).
• Levels of radiation in the Seville area (5.8 million kJ/m2 per year).
• Per formance of the solar equipment.
• Application of the RITE in terms of the percentage specified to cover energy needs.

The collectors, which are all located in the skylights of the roofs, are inclined at a 45º angle to allow for maximum absorption of solar radiation with regard to the latitude of the location of the buildings.

The temperature of the water leaving the collectors is approx. 60 ºC. In the first heat exchanger there is a thermal gradient of 10ºC. The water entering the accumulators has a temperature of around 45 ºC, which is the temperature of the water consumed in the installations.

The operating principle of this system is as follows:

The solar fluid (water + propylenglicol) is heated in the collectors and circulates towards the SHW accumulator. After passing through the heat exchanger, it transfers part of its heat to the (cold) water from the network contained in the solar SHW tank. From there, the fluid is pumped back to the collectors to be reheated.

SOLARMAC is currently working on several large solar heating installations which will allow it to undertake projects in the coming months for installations of up to 500 m2 of useful sur face area.

Iago Castro Pérez
Project Technician