Selasa, 17 Mei 2011

Indoor Pool Dehumidification

Most people associate the interior of 2 indoor pools with high humidity, stuffy air and steamy windows and walls. The air quality of pool enclosures is gauged by several key factors, with the most common being relative humidity. The vapour pressure differences between pool water and air cause continuous evaporation producing high humidity conditions in the pool room. During summer months, outside air that enters the pool room through make-up air handling systems can increase the moisture content of the indoor air because it has relative humidity that is equal to the pool room.

Warm air retains the moisture, but cooler walls will cause moisture to condense. Finally, high humidity is uncomfortable for those using the pool room.

The warm moist air is condensed and cooled at a dehumidifier coil thus transferring all of the energy to a refrigerant. The recovered energy can be given back to the air stream at the reheat coil in the form of sensible heat thus recovering almost 100% of the energy. This heat is returned to the pool room environment maintaining the appropriate air temperature. Dehumidifier designs offer alternate heat sinks such as a water cooled heat exchanger to heat the pool water in addition to the air. The calculation of evaporation rate takes into account various factors, including pool water temperature, air temperature, humidity level, water agitation, wet surfaces and air flow rates.

The air velocity near the pool surface needs to be kept low as high velocities can double the evaporation rate, greatly reducing humidity control efficiency and increasing energy consumption. Lower air velocity at this point also increases the comfort level of pool users.

Supply air is directed to areas of low R-Value, placing a layer of warm dry air to blanket the vulnerable surface such as exterior glass. Glass on exterior walls will readily form condensation, particularly when outdoor air temperatures are low. Commercial pool enclosures must account for all three factors: evaporation, make-up air and people. Residential pools do not have the make-up air loads nor the people loads, thus their moisture calculations are reduced to evaporation content only.

Everybody out of the pool!

Lightning can strike indoor swimming pools. Here's how: Lightning strikes a power pole outside the pool building. A surge of current races along the electrical wires from the hit power pole to the pump in the building. The pump moves water and, therefore, contains water; water conducts electricity. The current surge flows from pump wires into pump water, which conducts the electric current into pool water and water splashed around the area.

This endangers people in the pool and walking on the wet floors, because the current then flows through people to ground, along any of various paths: A person standing in the pool, one climbing on the ladder, another touching the underwater lights.

Metal can conduct a bolt's current. Current flowing from a lightning strike is fearsome — averaging about 25,000 amps.

Richard Kithil of the National Lightning Safety Institute and Kevin Johnston, a senior consultant conclude: suspend all pool activities until 30 minutes after the last observed thunder.

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