INGENIEUR
INGENIEUR
main factors to be considered during cooling load calculation are:
1. Conduction( heat gain from walls, roofs, windows, etc).
2. Radiation( solar heat radiated through the glass).
3. Internal heat gain( from people occupying the building, the lighting and other heat generating equipment, e. g. servers).
4. Infiltration( air leaking into or out of a space through doors, windows and small cracks).
5. Ventilation( introduction of outdoor air into a space to dilute or remove contaminants from the indoor air).
For conduction and radiation, the climate data used is based on the geographical location and the orientation of the building. For instance, for a row of terraced shop houses in which the building is located with a west facing wall, the afternoon heat load will be more significant than the morning heat load. On the other hand, in the case of internal heat gain, the schedules of occupancy have to be taken into consideration when estimating the cooling load. Estimating the cooling load taking into account these detailed inputs will ensure that the equipment is sized according to the real peak load of the building space to be air-conditioned.
The cooling load estimation phase is followed by the equipment selection phase. This process involves sizing the Cooling Tower, Chiller, Air Handling Units, Condenser Water Pump, Chilled Water Pump, Air-Side Ducting and Water-Side Piping. Engineers are challenged to make energy efficiency a top priority during equipment selection and to select the latest energy efficient technologies which can meet the design specifications. One of such technologies is the variable speed drive design for the motors on Chillers, Pumps, Cooling Towers and Fans which can save a significant portion of the energy consumption in ACMV systems. Furthermore, equipment that use chlorofluorocarbon( CFC) and hydro-fluorocarbon( HCFC) refrigerants must be avoided as they cause harm to the environment.
Another issue is the location for the installation of the Cooling Tower because it requires an open space to discharge heat to the environment, a substantial amount of water, chemical treatment handling and generates noise. If there are residential buildings adjacent to the Cooling Tower, then noise pollution is a design concern.
Last but not least, during the construction phase, safety requirements must be adhered to in order to avoid site accidents. Safety officers must be in place to enforce the safety requirements. The ACMV system shall be installed in accordance with the requirements of the local authorities having jurisdiction over the work. These include:
●●
Tenaga Nasional Berhad( TNB).
●●
Jabatan Bomba dan Penyelamat Malaysia( BOMBA).
●●
Jabatan Kesihatan dan Keselamatan Pekerja Am( DOSH).
●●
Jabatan Alam Sekitar( DOE).
Summary
In summary, this article describes the common design issues concerning ACMV systems in Malaysia. It highlights the design guidelines and best practices for ACMV design with the objective of reducing design errors, omissions and providing ACMV services that better meet the needs of the society. This should lead to improvements in both the efficiency of the design process and in the subsequent implementation of ACMV design.
REFERENCE
[ 1 ] W. S. Stoecker & J. W. Jones. Refrigeration and Air Conditioning. New York, NY: McGraw- Hill, Inc., 1982.
[ 2 ] Jabatan Kerja Raya Malaysia. Guideline on Air-Conditioning System Design( Bab 3 – Kerja M & E). Unit Ukur Bahan CKM Ibu Pejabat JKR Kuala Lumpur, 2005.
[ 3 ] 1997 ASHRAE Handbook: Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, 1997.
[ 4 ] Malaysia Standard MS 1525:2014. Energy Efficiency and Use of Renewable Energy for Non-Residential Buildings- Code of Practice. Department of Standards Malaysia, 2014.
[ 5 ] System Design Manual. Carrier Air Conditioning Company. Carrier Corporation, 1972.
[ 6 ] Arthur A. Bell Jr.. HVAC Equations, Data, and Rules of Thumb. McGraw-Hill, 2000.
38 VOL 71 JULY- SEPTEMBER 2017