We recommend consulting engineers to specify self-contained units and, if permitted by subsurface conditions, to apply a geothermal design.
by Alfredo Sotolongo*
The most economical energy to produce is the one that is saved!
We have always considered it our responsibility to contribute to consulting engineers in their designs to achieve more efficient and environmentally friendly air conditioning systems. This is why we select to represent manufacturers whose equipment offers a positive contribution to achieve this goal.
On this occasion I would like to refer to self-contained units. In which are inside the cabinet the components that complete the refrigeration circuit: compressor, water-cooled condenser, expansion valve and evaporator. In addition, the valve to convert the unit into hot/cold where the evaporator becomes a heating coil, while the condenser becomes a cooling coil.
In most self-contained equipment, the water that passes through the condenser, when operating for cooling, is passed through a water/water heat exchanger combined with a cooling tower or directly to the cooling tower.
When operating for heating, a small boiler is added to the condensing water circuit to keep the water temperature of the tower as constant as possible during the coldest winter days. In the case of the cooling tower, the outside air temperature varies considerably as it changes from summer to winter and vice versa. Therefore, the temperature of the condensation water changes as the conditions of the cooling tower change.
Below the surface of the earth, the subsurface temperature is very constant regardless of whether it is summer or winter. Depending on the latitude the subsurface temperature is between 45°F and 75°F. One of the methods to be used that represents considerable savings in energy consumption is geothermal. The air conditioning system is supplied with pipes that can be installed horizontally or vertically at a certain depth to take advantage of the fairly constant temperature conditions around such pipes.
By keeping the subfloor temperature constant around the pipes, the air conditioning system only has to compensate for the changing conditions of the thermal load in the conditioned area through modulating volume supply fans combined with variable capacity compressors.
Fans connected directly to the motor offer very low sound operation, reduced floor space and easy maintenance. Compressors with variable capacity adapt to the thermal load of the conditioned area at the moment it changes either in cooling or heating.
Among the companies that have dedicated more economic and technical resources is WaterFurnace International, Inc. that remains tireless in researching and developing the best components to minimize the energy consumption of all its products. The production capacity of its modern factory is dedicated 100% to equipment for geothermal applications.
High-efficiency self-contained units comprise:
a) Multi-zone type units, variable or constant volume.
b) Modulating hot gas for humidity control.
c) Control of head pressure.
When these components are combined with supply modulating fans and variable capacity compressors in geothermal applications, the unit's electrical consumption is decreased and therefore the cost of operation is drastically reduced.
We recommend consulting engineers to specify self-contained units and, if permitted by subsurface conditions, to apply a geothermal design.
This is a design that offers the customer the lowest power consumption system available for offices, apartments, shopping centers, among others. Each tenant is responsible for paying for their electricity consumption of the air conditioning and they only have to share the operating cost of the condensation water circulation pump.
If you need more information on this topic, please contact us through the mail [email protected]
* President of Protec, Inc., is certified as a professional engineer in Puerto Rico and in the state of Florida; He has more than 40 years of experience in the application and sale of systems and equipment for energy conservation. He is a member of ASME (American Society of Mechanical Engineers), AEE (Association of Energy Engineers), ASHRAE and was president of the Miami chapter of that association.
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