Human Comfort Analysis with SOLIDWORKS Flow Simulation (HVAC Module) in Bus Air Conditioning System

In Simulation by ateworks

By William


Designing a cooling system involves selection of cooling capability, sizing of ducting and maintaining good ventilation across the whole chamber. A good cooling system will definitely ensure high human comfort level.

A CFD analysis is carried out to understand the flow distribution in a bus cooling system. Human comfort parameter is obtained as well as by projecting the Predicted Mean Vote Index (PMV) and Predicted Percentage of Dissatisfied (PPD) values.

We will be using the SOLIDWORKS Flow Simulation to illustrate how we can study HVAC on the bus model below. (HVAC is defined as Heating, Ventilation and Air Conditioning)

Bus model with CFD

Bus model with ducting for Flow Simulation Analysis

SOLIDWORKS Flow Simulation HVAC modules come with extensive material database that can accurately simulate the heat transfer scenario in your cooling system.

Preview of material database

Sneak Preview of Material Database

Fan database is also available in SOLIDWORKS Flow Simulation HVAC modules. Hundreds of fans with the respective fan curve and flow data are readily available for selection.

fan database

Sneak Preview of Fan Database

SOLIDWORKS Flow Simulation HVAC modules allow us to consider the radiation source and parameters in our cooling system study as well. Location and direction of sun can be assigned to provide a close to actual scenario study.

CFD attribute

Air will flow from the Flow Inlets that is induced by the motor fan at the evaporator. The cool air will then flow across the internal ducting exiting the narrow outlet distributing the load over the interior of bus.


bus duct

Inlet Flow parameters can be assigned with its respective thermal parameter as well as humidity parameter.

bus parameters

In this case study we only consider the heat dissipated by human body.


Result and Discussion:

1.Goal Plot to indicate the parameters changes across iterations.



bus-graph22. Probing is available to investigate the details at point of interest indicating temperature on an average value of 25oC across the study domain. The results temperature and humidity seem to be decent in this case.




3. However, the average temperature and humidity itself might not be sufficient to ensure that we have an optimum design of cooling system. Let’s us further investigate with the PMV plots and flow trajectories in our case study.

4. The PMV results show non uniform plots on the driver seats and the rear end of the passenger seat. This gives us a pretty good insight of where is the improvement needs to be carried out. Design changes including the ducting outlet position, inlet flow rate and fan selection are some options available to obtain an optimum design.




5. Lastly we called out the flow Trajectories to understand the flow pattern and distribution in our case study. We can even animate the flow trajectories to get an insight detail of flow distribution. We want to unsure that the air throw is sufficient to reach the far end of our study domains with sufficient velocity. The objective is again to maintain human comfort level parameters.



SOLIDWORKS Flow Simulation, HVAC Module include industrial fans selection, radiation parameters and extensive material database to simulate the actual scenarios in you HVAC cooling system.

Flow Simulation aims to deep dive into the your cooling systems by extracting the temperature data, velocity profiles and the human comfort index ensuring you have the optimum design of cooling system before sending out for lab testing or prototyping.

Flow trajectories capabilities given you further understanding of the flow distribution in your system ensuring the optimum coverage of flows and ventilation as well as avoiding air stall and vortex.

There are no limits of trial when it comes to simulation analysis in the virtual environment. The best design comes from understanding how your system works and the impact to the end users. SOLIDWORKS Flow Simulation HVAC modules provide you the exact solutions to do that.

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