As the power of equipment such as photovoltaic inverters, power conversion system, and charging piles continues to increase, more and more large-scale new energy laboratories have been established, and the challenges facing laboratory design have become increasingly severe. Many equipment and devices under test (DUTs) have serious heat generation issues. Meanwhile, laboratories are constrained by site and building structures. It is now a focus of system design to utilize the existing space to arrange the inlet and outlet airflow and heat dissipation and output the most cost-effective solution.
By controlling the indoor temperature, a stable, safe, and efficient test environment is created to ensure accurate and authentic experimental data. Based on years of customer service experience in laboratories, Kewell has summarized effective methods for thermal design in power supply laboratories for your reference.
| Common thermal design solutions
There are four common types of thermal design solutions for laboratories: no heat dissipation design, duct alone, air conditioning alone, and a combination of air conditioning and duct.
| Key influencing factors in thermal design
Heat generation of equipment
The heat generation in the laboratory mainly includes power supply loss, loss from other heat-generating devices, etc.
Qtotal=Qpower supply+Qother
=P*(1-η)-Pf+Qother
Note: P represents the maximum power of the power supply or the actual maximum power in long-term operation of the platform. The higher the P value, the higher the costs of thermal design. An appropriate solution should be selected based on the actual laboratory planning.
Required airflow for equipment
In the design of a laboratory, it is necessary to ensure that the ventilation volume of the laboratory is greater than the air input of the equipment to guarantee that the equipment takes in cold air. Inadequate intake airflow within the laboratory will result in heat accumulation or fan idling, leading to equipment overheating.
KTotal=Kpower supply+KOther
=N1*Kf1+N2*Kf2
Outdoor environment
The outdoor environment has a significant impact on the thermal design of the system and is an indispensable aspect to consider in the design. This is mainly reflected in two aspects: temperature and humidity.
Temperature
The heat dissipation in a laboratory is mainly achieved by continuously drawing in cold air and exhausting hot air to carry away the generated heat. When the outdoor ambient temperature is high, the heat-carrying capacity of hot air decreases, resulting in poor thermal convection and ineffective heat dissipation.
Humidity
When the air contains more moisture, its heat capacity is low, and its ability to carry heat is insufficient, leading to poor cooling effects. Additionally, it may cause condensation inside the equipment, affecting the operation of the system.
Duct design
The focus of duct design lies in its rationality and efficiency. Scientific design can achieve to the greatest extent the uniform distribution and rapid renewal of cold air indoors, ensuring that hot air does not stagnate, recirculate, or cross-mix, thereby guaranteeing smooth operation of the cooling system.
Safety: The duct should be coordinated with the building structure to avoid adversely affecting the overall safety of the building.
Duct layout: It is recommended to reduce bends and distances in duct design to ensure smooth airflow.
Vent position: Since hot air has a lower density than cold air, the exhaust vents should be positioned higher and farther away from the air intake to prevent hot air from being re-inhaled into the room.
Vibration: Excessively fast airflow velocity within the duct can cause vibrations in the duct structures. It is recommended to keep the air velocity below 10m/s.
Aesthetics: The duct should harmonize with the building’s exterior so that it will be more aesthetically pleasant.
Selection of fans and air conditioning
Reasonable selection of fans and air conditioning can enhance experimental efficiency, ensure experimental safety, and improve the working environment; at the same time, it caters to the needs of different experimental settings, contributing to energy conservation and operation & maintenance.
Introduction to the fan’s nameplate:
| Design principles
In the thermal design of a laboratory, the parameters for fans, air conditioning, and ducts should be determined based on specific conditions, but the general design principles are as follows:
Thermal design is to ensure the safety, practicality, and environmental friendliness of the laboratory, while also guaranteeing a suitable operating temperature. The main design principles for equipment ventilation and heat dissipation in the laboratory are as follows:
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Increase the flow velocity of convective media to carry away more heat.
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Increase the temperature difference to reduce the temperature of the convective media surrounding the heat-dissipating object.
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The duct should be as short as possible, to reduce air resistance within it.
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Increase the ventilation area by adopting shapes and installation positions that facilitate convective heat dissipation.
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It is preferable for the cross-sectional dimensions of the duct to match the outlet of the fan to avoid increased resistance loss due to cross-section transformation.
Precautions
Based on the above content, various forms of duct for laboratories can be designed simply, with the optimal scheme selected based on the equipment’s heat generation power, architectural characteristics, and the budget for thermal treatment. Meanwhile, the following precautions should also be noted during the design process:
| Case study
A third-party laboratory has set up a 600KW photovoltaic and energy storage testing platform, equipped with three 225KW AC power supplies of the Kewell A2000 series and one 600KW DC power supply of the Kewell D2000 series. The customer’s laboratory is an enclosed room with a total area of 20 m2 and an effective equipment layout area of 10 m2. An additional 10 m2 need to be reserved for the area where the DUT will be placed.
Power supply layout-related parameters
Actual site layout
On top of the advantages of Kewell's D2000 and A2000 series products in terms of efficiency, the system adopts a duct + air conditioning thermal design. The air conditioning is only used for reducing the heat spilled into the space and for initial cooling of incoming air from the outside. The heat generated by the equipment is exported through the duct, significantly reducing costs.
Photo of the laboratory
A stable and reliable laboratory thermal system can reduce the construction and operational costs of the laboratory, extend the service life of equipment, and ensure testing accuracy. Kewell is willing to share mature and efficient design solutions with more customers to support the development of various industries.
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