Calculation of Cooling Load of Central Air Conditioning UnitUsing Computer Program

Abstract

This study is calculation of cooling load for central air condition unit using computer program (Hourly Analysis Program), the case which studied was building of faculty of engineering in Elimam Elmahadi University. According to imprecision of results which obtained by manual method (mathematical equations) which correlate with errors, stress and loss of time and difficulty of transference between different units of measurement (Metric and British) and data entry. Hourly Analysis Program (HAP) is considered as important electronic engineering programs which calculates different thermal loads and it has the ability to save time and it gives accurate calculations, results and detailed reports about thermal loads depends on the information's provided by the user, and it can also simulates to decrease consume of electricity and fuel. The computer was used (Hourly Analysis Program) in calculation of cooling loads for building of faculty of engineering in Rabak city, the results which was obtained that the total cooling load which was required to condition the building is (483kW) and the total sensible cooling load is (353.4kW) and the maximum load occurs in December at (4p.m), while the results which was obtained by the manual method (mathematical equations) is that the total cooling load was (372.065kW)and the total sensible cooling load(355.409kW) and the maximum load occurs in June at (4p.m). The reasons of variation between two methods that is Hourly Analysis Program concerning with atmospheric clearness number and it's average ground reflectance on landscape and surrounding areas whether it's (new concrete or old concrete, bright green grass, crushed rock, bitumen and gravel roof).as well soil conductivity underground ( sands, silts ,clays, loams),more over a building land that should be well studied and underground (floor above conditioned space, floor above unconditioned space, slab floor on grade , slab floor below grade), in addition to the definition of doors and windows with entire details regarding(details of the glass layers and type of gas that exists between in these layers),also a precise definition for lighting ceiling (in terms of it's free lighting, overhead lighting fixture used in the space, recessed unvented, recessed vented and free hanging) and task lighting all of these loads do not bother with the manual method so this variation resulted in addition to some of the loads that do not bother them accurately. This research was identified the different types of cooling systems, and was given a comprehensive and detailed study about Hourly analysis program and how to use it. Where it used to calculate the total cooling load and sensible cooling load, in addition to the use of the manual method to calculate both maximum cooling load and sensible cooling load.