ABSTRACT

Automatic hydraulic ram is an environment friendly device uses energy resource to pump water for domestic or agricultural use. Since being superseded by pumps using electrical or fossil fuel energy nearly a century ago, they are now coming back into favour in many parts of the developing world. In the past, hydraulic ram has been designed by rules-of-thumb having limited scientific basis. On-site adjustment has been used in the hope of rectifying the inevitable shortcomings of this process and ideal performance is rarely achieved. The present proposal for optimum design allows relevant system parameters (including the beat frequency) to be selected prior to installation. The report shows how a ram system may be designed using two simple equations containing empirical factors dependent upon ram size, delivery head, material and wall thickness of the drive pipe and the configuration of the waste valve.

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ABSTRACT

The thermal performance of two passive cooling systems under hot and humid climate condition is experimentally investigated. The experimental results were obtained from a test cell and a controlled cell with identical walls but different roof configurations. The passive cooling system applied to the test room is cooling cell on roof and the process is natural evaporation of water. The experimental results obtained from the test cell are compared with the closed and no passive cooling controlled cell. An experimental study of passive cooling roof was carried out for a typical summer day of June in Bangladesh. The proposed roof design is composed of a metal plate ceiling over which lies a bed of rocks in a water pool. Over this bed is an air gap separated from the external environment by a plane sheet plate. The upper surface of this plate is painted with a white color to increase the radiation reflection process during daytime.

Several passive modifications have been introduced to the roof in order to reduce indoor air temperature in hot climates. An experimental investigation, employing passive procedure, has been carried out to study the possibility of reducing air temperature in buildings. The results show that the air temperature can decrease with a range from 6 to 10 °C. This decrease can further be lowered by 2 to 3 °C if night natural ventilation of buildings is allowed.

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