Improving the Performance of HVAC Systems with CAE
The performance of HVAC systems is a critical issue in their design process. Experience shows that following the installation of a ventilation or heating system, a number of problems can occur that affect the performance and comfort factors. Ecosystems frequently encounter disruptions as a result of increased pollution factors. However, almost every time this occurs, the anomaly in the HVAC system’s operation results in a substantial increase in the utility bill.
Who’s responsible for this and how can we fix it? If the source of the problem is related to improper functioning of heating and cooling, then the dysfunction typically has a technical root. This can be resolved fairly easily by specialized HVAC service providers.
However, if the problems encountered are due to the poor performance of the HVAC systems, the improper positioning of the vents or heating, inadequate documenting of the building, inadequate design of utilities, or environmental factors that exceed the accepted limits of pollution, then the problem is much more complicated. In cases such as these, a comprehensive analysis of all disturbing factors must be carried out, and it should be accompanied by engineering simulation. Based on the results of these simulations, an optimized redesign of the HVAC system should be implemented. Implementing a solution at this stage is far more costly than if the simulation had simply been added to the design process from the beginning.
Performance of HVAC Systems with Quality Control
The main goal for an HVAC system is to provide proper airflow, heating, or cooling to each space, either in a home, office or industrial building. Just like any technical project, the engineers and architects should assure a quality control assessment is carried out based on standard comfort and efficiency criteria. The criteria needed to certify the performance of HVAC systems should be based on:
- Properly dimensioning for comfort airflow, and heating and cooling loads calculated for each room
- Respecting installation requests, according to the manufacturer and design specifications
- Installing a return system sized to provide correct return air flow
- Having projected return ductwork for proper airflow circulation to the fan, and avoiding air intrusion from polluted zones
- Evaluating balanced air flows between supply and return systems to maintain neutral pressure in the indoor spaces
- Optimal charging with a refrigerant.
How to Design and Install an HVAC System
To ensure optimal design, accurate dimensions, and a smooth installation, a couple of key methods should be used. Firstly, a simulation analysis of the airflow is recommended for any HVAC system. Other quality control measures are guided by standards or special HVAC manuals that are used in different regions and industries.
The next few steps should be followed in the design and installation of the HVAC system to ensure efficiency and thermal comfort:
- Calculating room-by-room loads and airflows
- Layout duct system on the floor plan
- Optimal sizing of the duct system
- Test HVAC equipment to sensible load
- Installing equipment and ducts according to design specifications, using installation requirements and procedures
- Test the system to see if it is properly sized, has proper air handler fan flow, and proper plenum static pressures.
Eliminating Performance Problems with Better Planning
The features offered by simulation tools can be used to virtually test and optimize the designs. This facilitates cost reduction, investment control, and the enhancement of the overall performance of HVAC systems. SimScale is the world’s first full-cloud 3D engineering simulation platform, which allows you to start with CFD and FEA simulations from a standard computer. All you need is an Internet connection.
Avoiding Thermal Comfort Problems
Environmental factors could be controlled by the HVAC equipment, but optimum thermal comfort is only provided if the heating, ventilation, and air conditioning systems are well designed to meet all specific indoor conditions.
A very good example of optimizing efficiency and comfort using simulation methods is this SimScale car cabin airflow analysis. In this case, the internal airflow simulation is performed by using the steady-state, natural convective heat transfer analysis.
The final simulation results show the airflow velocity contour through the car cabin and surface streamline figures depending on the rate of cooling in the vehicle. These results are very valuable as they inform the design of internal car ventilation and heating systems.
While air temperature is easily controlled, the radiant temperature has a greater overall influence on heat loss or gain. Air velocity and humidity are also important factors in maintaining thermal comfort.
Economic reasons and geo-climatic changes push HVAC engineers to find more efficient ways to control energy, save money, and reduce pollution with efficient airflow management and better placement.
More specialized energy-saving strategies are used for indoor spaces with special functions like server rooms.
For optimal cooling systems, simulation software could provide optimization ideas such as the server placement in the space, changes to the design for optimal airflow distribution, thus achieving better results with the ventilation system.
This is the case with this server room cooling analysis, which demonstrates how a server room cooling system could be optimized with a thermo-fluid analysis. The simulation results allow accurate evaluation of the necessary power required for the cooling system under different operation
The simulation results allow an accurate evaluation of the necessary power required for the cooling system under different operation conditions and offer a detailed look at the resulting velocity and temperature fields inside the server room.
The simulation also illustrates how different layouts of the server room can be adjusted in a very early design phase with less physical testing.
Reducing the Noise Level
Effective noise reduction is important when creating a more pleasant living and working environment. The most common sources of noise pollution in any building are related to fans, variable air volume systems, grilles and diffusers, rooftop units, fan coil units, chillers, compressors and condensers, pumps, standby generators, boilers, and cooling towers.
The alternative solutions that are currently available for noise reduction include: using silent ventilation equipment, protecting HVAC components with silencers and insulation materials, or implementing a noise optimization analysis. Using acoustics simulation, you can perform multiple natural and induced frequency analyses of complex geometries for different room or car cabin configurations.
If you want to learn more about how you can improve the performance of HVAC systems, just sign up for SimScale’s 14-day free trial and start by copying one of the HVAC templates or following a webinar on the dedicated industry page for HVAC applications.
This case study shows how the Austrian company IBEEE optimized the airflow of a ventilation system by 40%.