Automatic temperature and humidity regulation – Humidity control
Reexamination Certificate
2001-06-05
2002-10-22
Tapolcai, William E. (Department: 3744)
Automatic temperature and humidity regulation
Humidity control
C062S176400, C137S456000
Reexamination Certificate
active
06467694
ABSTRACT:
BACKGROUND
1. FIELD OF THE INVENTION
This invention relates to cooling of buildings, particularly to cooling by absorption and removal of heat from solar energy from the outer surface of buildings, thereby obviating the necessity of expensive and energy-wasting systems for removing such energy. The invention further relates to a fail-safe design wherein any failure of a component of the system will not result in a catastrophic spillage of water on the surface being cooled.
2. DESCRIPTION OF THE PRIOR ART
The desire and need to provide cooling for buildings and structures is as old as the art of constructing human habitation. Humans perceive “comfort” over a very narrow temperature range. Below about 18 degrees Celsius, the average person has the perception of cold. Above about 27 degrees Celsius the average person feels uncomfortably warm. From the very beginning, the concept of a habitable structure involved providing protection from the elements, including natural temperature variations beyond the foregoing comfortable range.
From the earliest use of mud and leaves as insulation, humans have sought to perfect the environment by the use of habitats. For much of the time, the consumption of resources and the use of power, was secondary to the achievement of a controlled environment. The prior art clearly shows the desire for achievement of climate control, without consideration for the inevitable failure of the system components, or the consequences of such failures.
As early as 1937, Holder, in U.S. Pat. No. 2,069,150 (Jan. 26, 1937), recognized that not only was evaporative cooling of structures a desirable means of cooling, but just as importantly, various systems and devices that had previously been used for cooling roofs were found faulty in cost of maintenance, consumption of water and also by reason of mechanical defects. While recognizing that mechanical defects were an impediment to the practical use of water for cooling roofs, neither Holder, nor any other prior art that I have found in the intervening fifty-six years addresses the issue of component or system failure.
Any system applying water, or another fluid, to a roof for cooling purposes must consist of at least pipes to carry water, valves to apply or restrict the application of water, and a control system to operate the valves. If a pipe fails—which can happen at any time since the most practical pipe to use is PVC—a material attacked by sunlight over time—water can be delivered to the roof in uncontrolled quantities. A failed valve can deliver unchecked water, or fail to deliver water when required. While solid-state electronics today are quite reliable, a control system cannot be presumed to be failure-free.
Holder raises the possibility of “mechanical defect”, but does nothing to address the issue of what impact it might have when an inevitable failure occurs. I believe that for this very reason, a concept that has been known for a century has never been accepted as a conventional means of structure cooling and energy savings.
Another patent to Holder, U.S. Pat. No. 2,266,321 (Dec. 16, 1941), addresses the “prevention of excessive heat accumulation in exposed surfaces such as roofs.” Importantly, Holder recognizes that evaporative cooling efficiently removes energy, while the excessive application of fluid on the surface decreases the effect. In his '150 patent, supra, Holder described a piping and spray system using a continuously applied spray of water. By first describing continuous water spray, then adding an interrupted spray, Holder improved upon a basic concept of using water for cooling purposes. While envisioning a thermostatically controlled valve to interrupt the flow of water, holder failed to contemplate the consequences of his own analysis.
Holder correctly describes the “initially high roof cooling efficiency” as water is initially applied to the roof surface. He then continues describing the action as it progressively and rapidly approaches the condition of low evaporative cooling efficiency where the main reliance is be placed on the cooling effect of the water per se. One liter of water absorbs 570,000 Calories in the transition from liquid to a gas or vapor. The heating of water to absorb energy absorbs only 1,000 Calories per liter of water, per degree Centigrade. Holder then proceeds to describe a process wherein a valve is thermostatically controlled for the application of water to the roof. Unrecognized is the effect of pooled water, rising to the temperature that is required to turn the valve on, thereby applying more water on water. This is an effect already recognized as undesirable. Holder fails to assure that water is applied without the possibility of accumulating water on the surface. Under such condition, the accumulated water may not provide any cooling.
U.S. Pat. No. 2,506,936 to Murray (May 9, 1950) continues the refinement of the cooling process by first reiterating the correct statement; “If only a small amount of water is placed on the roof, the evaporation is highly accelerated as compared to what would be if the roof surface were flooded with water.” Murray's solution is the addition of a time delay after a first application of water, before permitting a succeeding application of water. At this point, the concept fails in several respects. First, Murray describes a means of cooling the thermostat as water is applied to the roof. If the thermostat is cooled by application of too great a flow of water, the roof receives to little water. If the thermostat is cooled by too little water, the roof receives too much water. In this procedure, the surface to be cooled is not directly sensed for the correct amount of water to achieve optimal cooling. Murray, as all others, fails to address the problem of system or component failure, and the possible spillage of uncontrolled water.
U.S. Pat. No. 4,761,965 to Viner (Aug. 9, 1988) describes a very specific arrangement of an evaporative roof cooling system. Viner describes a “plurality of water distribution . . . nozzles, a “conduit means”, a solenoid valve, and a “temperature measurement means comprising a thermistor”. Viner, like his predecessors, espouses the need to apply water in a thin film, allow it to evaporate, and then repeat the application. Also like his predecessors, Viner falls into the trap of presuming that a timed cycle of water on/ water off will achieve the goal of optimum application of water. This timed sequence will never account for the variations in temperatures, variations of the water absorption of the roof material, variation in relative humidity, wind factor, as well as other factors that impact not only the rate of cooling of the roof, but also the rate of evaporation. Consequently, Viner fails in his goal to apply an optimally thin film of water.
Viner boasts “electrical power usage for the system is essentially zero”, but describes an electrically operated solenoid control valve, which is continuously energized. Viner neglects the power requirements of the valve, in addition to the costs associated with wiring the valve and control systems to the building wiring. Viner, as before, does not address the possibility of failure of a component of his system.
No known prior art that I have found, from as early as Crawford, U.S. Pat. No. 964,464 (Jul. 12, 1910) through Strussion, U.S. Pat. no. 6,112,538 (Sep. 5, 2000), has recognized the fact that water on the roof of a structure carries an intrinsic risk of damage to the structure. Several possibilities contribute to that risk. Much of the prior art discloses the use of a thin film of water to effect an evaporative cooling on the structure. While early patents promote the use of moisture absorbing pads to keep a roof wet at all times, later, more advanced patents teach the deleterious effect of too much water. Earlier patents expound the use of a control valve, with later patents expounding to the use of multiple valves to control different portions of a roof. While the use of multiple valves where each valve is delivering water to only a portion
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