spa passive cooling performance analysis

8/13/2019 Spa Passive Cooling Performance Analysis

1/17

Performance Analysis PASSICE COOLING SYSTEMS

PDEC systems have been used with various types of cooling devices such as, spraydevices (pressure and ultrasonic nozzles), aspen fibre pads, corrugated cellulosepads, etc


2/17

Givoni [22] has developed performance equations for the shower tower. It consists of an open shaft with showers at the top and collecting pond at the bottom. Thewater collected at the bottom of the pond is re circulated by a small pump. Whendrops of water are sprayed vertically downward from the top of the shaft, they entraina volume of air which flows down the shaft with falling water. The air thus getscooled and can be used for cooling of a building.


3/17

CASE STUDY Details

1. Brief design details2. Technical details3. Results4. Performance

Report hand written max. 2000 words


4/17

Roof Surface Evaporative Cooling (RSEC)

In a tropical country like India, the solar radiation incident on roofs is very high in summer,leading to overheating of rooms below them. Roof surfaces can be effectively andinexpensively cooled by spraying water over suitable water-retentive materials (e.g., gunnybags) spread over the roof surface. As the water evaporates, it draws most of the requiredlatent heat from the surface, thus lowering its temperature and reducing heat gain. Besides,evaporation also cools the air above the roof. The cool air slides down and enters the livingspace through infiltration and ventilation, providing additional cooling. This is an example of thepassive indirect evaporative cooling technique.

For installing a roof surface evaporative cooling system, the following points need tobe taken note of:1) Suitable waterproofing treatment of the roof should be done.2) The roof must be covered with water absorptive and retentive materials such as gunnybags,

brick ballast, sintered fly-ash, coconut husk or coir matting. On account of theirporosity, these materials when wet, behave like a free water surface for evaporation.The durability of such materials is rather good, but they have to be treated for firesafety.3) During peak summer, the quantity of water needed is approximately 10 kg/ day/ m2 ofroof area.4) The roof must be kept wet throughout the day using a water sprayer. The sprayer canbe manually operated or controlled by an automatic moisture-sensing device. Thesprayer usually works at low water pressure which can be achieved either by a waterhead of the storage tank on the roof, or by a small water pump.


5/17

Performance AnalysisThe effectiveness of RSEC depends on: ambient air temperature and humidity intensity of solar radiation

wetness of the roof surface roof type


6/17


7/17


8/17


9/17


10/17

Earth Coupling This technique is used for both passive cooling as well

as heating of buildings, a feat which is made possible bythe earth acting as a massive heat sink. The temperatureof the earth's surface is controlled by the ambient

conditions. However, the daily as well as seasonal variations of thetemperature reduce rapidly with increasing depth fromthe earth's surface.

At depths beyond 4 to 5m, both daily and seasonalfluctuations die out and the soil temperature remainsalmost stable throughout the year. It is equal to theannual average ambient airtemperature at that place.


11/17


12/17

Performance AnalysisThe performance of the earth-air pipe system depends on the rate of heat transferbetween the air and surrounding earth, which in turn is governed by the resistancesoffered by:(i) the convection between air and inner surface of the pipe,

(ii) conduction through the thickness of the pipe wall, and(iii) conduction through the surrounding earth.

performance of the earth-air pipe system depends on system parameters (depth of the pipe from the earth's surface, its length and radius, thermal conductivity of the pipe material, and air speed through the pipe)

soil parameters surrounding the pipe (thermal conductivity, specific heat, densityand moisture content) weather conditions (solar radiation, ambient temperature) earths surface conditions (shaded, blackened, white -painted or wetted with water)


13/17

The temperature TAL at the end of a pipe of length L can be written as


14/17


15/17


16/17


17/17

CASE STUDY Details

Earth-air pipe systems have been installed at many places in the country.RETREAT building, Gwalpahari, Gurgaon; Dera Library, Radha SwamiSatsang, Beas, Dilwara Bagh; Country House of Reena and Ravi Nath,Wazirpur, Gurgaon, etc.

spa passive cooling performance analysis

Documents