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Blow-through (BT) and draw-through (DT) modes are the two common types of air handling unit (AHU) configurations that are prevalent in heating ventilation and air conditioning (HVAC) systems in existence. The arrangements of a supply fan and a cooling coil in these systems have advantages on each other in terms of cooling coil loads, moisture remov...
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Citations
... Since, ADP condition corresponds to the lowest saturation limit of air passing through the coil, the vapor pressure at this temperature (tadp) is determined from the modified Clausius-Clapeyron equation [17][18] as: ...
Warp-around heat pipes (WAHP) belong to a special class of recuperative heat exchangers that transfer heat from inlet to outlet locations via thermal gradient, without using any energy. In the present work, effects of various mechanical parameters on the performance of a WAHP dehumidifier system that are based on the underlying principles of heat and mass conservation are presented primarily from a theoretical point of view. A simplified methodology pertaining to wet cooling coils is applied here for defining the case of moisture condensation during precooling process at WAHP evaporator. Inlet air temperature, inlet humidity ratio, air mass flow rate, dehumidifier outlet temperature and effectiveness are the main operational parameters considered in this study. On the other hand, comparative performance study of the WAHP system is done through an other set of thermodynamic parameters like the supply air temperature, supply humidity ratio, specific coil load and recovered enthalpy. The subtle variations in these factors against the operational parameters not only help in stipulating functional characteristics of the WAHP but also allow HVAC designers to make informed decisions for system design and performance without relying entirely on manufacturer's equipment data.
... A building is any permanent or temporary structure enclosed within exterior walls and a roof including all attached apparatus, equipment, and fixtures that cannot be removed without cutting into ceiling, floors, or walls. These structures in the past were built by people not schooled in any kind of formal architectural design or with identifiable building techniques rather they depended on the cover the structure of the earth could provide for them purposes of shelter, warmth and security [2]. Energy is the property of matter and radiation that is manifested as a capacity to perform work, especially to provide light and heat, or to work machines. ...
this study evaluates the building energy performance for an office complex with different building materials: block work material with a concrete slab as roof with a view to establishing energy performance as well as design variables that can be used to facilitate low energy building designs in Nigeria. This was achieved through energy-audit end use analyses from field work (empirical approach) and computer simulation. SAVISCAD software was used to conduct the computer simulation component of the research. The simulation involves evaluation of architectural design variables identified from design guidance for low energy buildings as well as design recommendations for tropical climates influence on building energy performance in Federal University of Technology, Akure. This study focuses on specific design recommendation with the aim of informing further office design regulations in Nigeria. The result indicates that block work material with a concrete slab as roof is not suitable for office designs because it has a high required cooling capacity of 1.61TR which is considered too high compared to other materials to achieve human comfort in an office complex.
... The BPF can be used to compute the outlet absolute humidity X out,eva as (Sarkar 2013(Sarkar , 2015Mansour and Hassab 2016): ...
This paper presents the validated Modelica model of a Menerga™ Adsolair™ type 58 Air Handling Unit. The unit consists of two fans, four dampers, three air filters and further allows heat recovery (including free cooling), indirect evaporative cooling and active cooling. The first principles model uses manufacturer data sheet information and optionally also measurement data to calibrate some parameters for increased accuracy. Model validation is based on measurement data and results in an average normalized absolute error for the electrical power consumption of approximately 1%. A custom developed control strategy is compared with the measured performance of a proprietary controller. The model is available open source as part of the IDEAS Modelica library.
... The coil surface will be wet and results in condensation of vapor from the incoming air stream, if its surface temperature determined by Eq. (3) is below the inlet dew point temperature. In this case, the saturated humidity ratio of the coil at its effective surface temperature can be easily determined as per the methodology shown in an earlier work [21]. ...
... (12)- (19), first set of coil surface temperatures at inlet and exit points are obtained. These are substituted back in Eq. (21) and the procedure is iterated until convergence is attained. The factor 'r' is revised after jth iteration step as: ...
... The inlet condition and the resulting ADP affect the accuracy of the model. Typically, ADP of a chilled water coil is above 4 • C [21]. Considering a range of 9-22 • C for design supply temperatures and an inlet humidity range of 0.007-0.022 ...
... Here, a modified form of the Clausius-Clapeyron equation for vapor pressures is applied for deriving a simple equation for DPT. From literature study, it can be seen that the modified Clausius-Clapeyron equation gives acceptable vapor pressures with minor deviations in results corresponding to temperatures within the scope of comfort air cooling applications [40,41]. ...
... As per modified Clausius-Clapeyron equation [41], the vapor pressure at saturation temperature (or DPT) is: ...
A framework for creating thermal zones in a building for effective and efficient Heating Ventilation and Air conditioning (HVAC) system design is introduced here. This method is based on simple “sort and eliminate” schemes and requires design cooling loads of conditioned spaces obtained from load calculation tools as primary input. The developed methodology is applied for creating thermal zones, determining corresponding supply conditions and ascertaining sizing of a dedicated outdoor air system (DOAS) with local recirculating units. A simulation study on a prototype-building model shows that a DOAS coupled with zoned recirculating systems that serve distinct thermal zones in a building (zoned model) perform comparatively better in controlling both space temperatures and humidity without significantly compromising HVAC energy and chiller loads than un-zoned HVAC systems serving the whole building as a single thermal block (un-zoned model). The consistency in the performance of zoned HVAC systems is verified by applying three different simulation weather files for New Delhi. Better performance along with logical and computational simplicity makes this design procedure a good alternative to traditional methodologies.
