HVAC Systems Performance Optimization with CAE
Performance is a critical issue in any HVAC system design. Experience shows that many times after installing a ventilation or heating system, a number of problems can occur affecting the system’s performance and comfort factors. Quite frequently we can have ecosystems disruption sources related to increased pollution factors. But almost every time, any anomaly in an HVAC system’s operation entails a substantial increase in the utility bill.
Who’s responsible for this and how to fix it? If sources are related to improper functioning of heating and cooling, most often the misfunction has technical reasons relatively easy to be fixed by specialised HVAC services providers.
But if the problems encountered are due to the poor performance, the bad positioning of vents / heating, states of discomfort due to inadequate documenting of the building and design of utilities or environmental factors that exceed the accepted limits of pollution, then things are much more complicated. It takes a comprehensive analysis of all disturbing factors, accompanied by simulating ideal situations. Based on the results of these simulations, an optimized redesign of the HVAC system will follow. And this is far more costly than if from the beginning simulation would have been added to the design process.
How to ensure HVAC systems performance with quality control
The main goal for an HVAC system is to provide proper airflow, heating, and cooling to each space, either in a home, office or industrial building. Usually, like in any technical project, the constructor, and the utility provider should assure a quality control assessment based on standard comfort and efficiency criteria. The criteria needed to certify HVAC systems performance 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 air flow circulation to the fan, 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
For properly designing, dimensioning, and installing, a couple of methods could be used. First of all, for any HVAC system, a simulation analysis of the airflow is recommended. Other quality control measures are guided by standards or special HVAC manuals 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:
- Calculate room-by-room loads and airflows;
- Layout duct system on floor plan;
- Optimal sizing of duct system;
- Testing HVAC equipment to sensible load;
- Install equipment and ducts according to design specifications, using installation requirements and procedures;
- Testing the system to see if it is properly sized, has proper air handler fan flow, and proper plenum static pressures.
Eliminating HVAC systems performance problems with better planning
The quality of the HVAC equipment is critical in a wide range of applications, from home heating and ventilation to industrial ecosystems based on energy savings, thermal comfort, air quality or noise standards. Being compliant with various criteria, the design of HVAC systems is subject to testing, facilitated by engineering analyses.
The simulation types offered by simulation tools can be used to virtually test and optimize the designs, achieving cost reduction, investment control, and enhancement of performance. SimScale is the world’s first full-cloud 3D engineering simulation platform, that allows you to start with CFD and FEA simulations from a normal 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 provided only if the heating, ventilation, and air conditioning systems are well designed to meet all specific indoor conditions. While air temperature is easily controlled, the radiant temperature has a greater influence on heat loss or gain. Air velocity and humidity are also important factors in thermal comfort.
A very good example of efficiency and comfort gaining using simulation methods is this SimScale car cabin airflow analysis. Here 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 precious for better design of internal car ventilation and heating system.
Energy saving – a serious problem in HVAC systems performance
Economic reasons and geo-climatic changes push HVAC systems engineers to find better ways to control energy, save money, and reduce pollution with efficient airflow management and HVAC adjustment. More special energy saving is related to indoor spaces with special functions like server rooms. For optimal cooling systems, simulation software could show optimization ideas such as the server placement in the space, changes of the design for optimal airflow distribution and thus achieving results with the ventilation system. This is the case with this Server Room Cooling Analysis, demonstrating how a server room cooling system could be optimised using the SimScale thermo-fluid analysis. The simulation results allow evaluating the necessary power of the cooling system under different operation conditions, offering a detailed look at the resulting velocity and temperature fields inside the server room. That also shows how different layouts of the server room can be evaluated in a very early design phase with less physical testing.
Reducing the noise level
Effective noise reduction is an important factor in creating a more pleasant living and working environment. Most common noise sources in any building are related to fans, variable air volume systems, grilles and diffusers, roof top units, fan coil units, chillers, compressors and condensers, pumps, stand-by generators, boilers, and cooling towers.
The alternatives available for noise reduction include: using more silent ventilation equipment, protecting HVAC components with silencers and insulation materials, or implementing noise optimisation analysis. Using acoustics simulation technology based on the Finite Element-based solver integrated by SimScale, you can perform multiple natural and induced frequency analysis of complex geometries, for different room or car cabin configuration.
This case study shows how the Austrian company IBEEE optimized the airflow of a ventilation system by 40%.