Views: 1 Author: Site Editor Publish Time: 2023-03-24 Origin: Site
Creating a heat exchanger for a laser system for aesthetic or medical use.
It is crucial to take into account a number of variables while constructing a heat exchanger for an aesthetic/medical laser system (laser, IPL, RF, and ultrasound). An overview of a few of these key characteristics will be given in this essay.
Learn how much heat needs to be removed overall from the heat source, which may be a laser, IPL, RF, or ultrasound. The heat from our heat source will now be combined with the heat produced when the pump and fan are running, as well as some safety overhead. This is vitally important because if the heat exchanger is designed below that maximum heat capacity, our system would not operate under stable conditions for an extended period of time and would finally shut down from overheating.
The kind of liquid utilized in the heat exchanger and cooling system is crucial as well. The kind of liquid a system uses affects both the heat exchanger's construction materials and its actual thermal performance.
The heat exchanger must be made of medical-grade stainless steel tubing if deionized water is being used (such as 316 stainless-steel). The system will become contaminated and develop leaks if deionized water is used with non-stainless steel tubing.
The heat exchanger may be constructed with tubes made of materials other than stainless steel if the liquid is not corrosive. It's vital to keep in mind that adding inhibitors to corrosive liquids (such deionized water) doesn't totally cure the problem of corrosiveness; as a result, utilizing non-stainless steel tubing will offer the same problems outlined above, most likely at a slower speed.
The heat exchanger's available space is a crucial consideration. The right size must be determined while taking into account the thermodynamics and the cost-benefit analysis in order to construct the ideal heat exchanger. We will help you choose the right size by taking into account surface ratio, air flow rate, heat exchange area, and other variables.
A primary influencer of the performance of the cooling system is the ambient temperature. Any rise or fall in the ambient temperature or the temperature of the air passing over the heat exchanger will, when the system is in a stable operating condition, cause an increase or decrease in the temperature of the entire system, respectively. Also, it will become more challenging to remove the heat the closer the ambient temperature gets to the temperature of the liquid leaving the heat source. With an ambient temperature of 24° C, removing 600 watts of heat is very different from attempting to do the same thing with an ambient temperature of 30° C. Workplaces with air conditioning are often kept at a temperature of around 24° C in many Western nations, but in nations like China, India, and others, this is not the standard at all, and the outside temperature can rise as high as 32° C. The cooling system should be planned for an ambient temperature range of 30 to 32 degrees Celsius.
We can move forward with the actual heat exchanger design once we know the general requirements:
Size of the heat exchanger is important since it determines how much heat can be removed using the supplied liquid and the chosen ambient temperature. The design must account for the proper flow of both liquid and air as well as the pressure drop for each.
choosing a pump Several variables must be taken into account while choosing a pump. The ability of the pump to deliver the flow rate needed by the heat source is one of the most crucial requirements (diode, lamp, RF or ultrasound). Also, the pump's construction must use components that are compatible with the liquid we are using. When operating at the required flow rate, the pump's ability to tolerate pressure drops induced by the heat exchanger and other components of the cooling system, such as pipes, connectors, and more, is a crucial factor to take into account. With the information provided by the pump manufacturer, we must check and confirm that we can operate the pump and achieve the desired flow rate while managing the overall aggregated pressure drop we estimated for our system. It is necessary to tune the heat exchanger to achieve the highest flow rate with the least amount of pressure loss. The pressure drop range of 0.2 kPa to 0.3 kPa is typically used while designing the heat exchanger. Operating with pressure drop outside of this range can impair the thermal efficiency of the heat exchanger and shorten the pump's lifespan. The heat exchanger's ability to remove the desired quantity of heat at the stated flow rate depends on the length and radius of its pipework, which will also influence the pressure drop it will produce. By creating a heat exchanger with many circuits, we may solve this problem.
Fan selection - There are a number of factors to take into account while choosing the fan.
The entire amount of heat to be eliminated and the necessary cooling system performance determine the amount of air that is needed.
Maximum pressure drop permitted - To determine where on the fan's graph we will receive the necessary airflow in relation to the pressure drop produced on the heat exchanger's surface. The air speed across the heat exchanger's surface must be taken into account when analyzing the air flow. Air flow across the heat exchanger's surface, as well as the heat exchanger's actual size, depth, and fin spacing, all affect the pressure drop.
necessary level of noise
Liquid working temperature - When building a system with a liquid temperature above 50° C, it's important to make sure the fan is built to withstand these temperatures.
A crucial element to keep in mind is that we must strive to reach the ideal point while the design process is still in progress, taking into account the surface area for heat transfer, the surface area of the heat exchanger, the air flow speed, and the least amount of pressure drop. Our method may be made more efficient by changing the fin spacing and heat transfer area. Also, if we already know the pump's parameters, we may move forward with the thermal calculations for the chosen working point and select the particular fan based on the findings of those calculations for the air flow and pressure drop.
Guidelines for designing and installing heat exchangers:
It is critical to confirm that all of the parts are in sync with the heat exchanger and that the cooling system is operating at the right point after taking into account all functioning and thermal characteristics.
A specific welding standard is necessary in the case of deionized water with stainless steel heat exchanger tubing. Argon (inert gas) is used during welding to safeguard the welding environment.
If the heat exchanger is composed of stainless steel, it needs to be thoroughly cleaned at the conclusion of production. The removal of any oil deposits (by melting) and other welding process residues are included in this. To seal all of the heat exchanger's surfaces, it is crucial to finish the passivation process. The passivation process will take longer and consume more space the higher the heat exchanger's working temperature is.
To increase air flow and ensure a consistent flow across the heat exchanger, it is strongly advised to install the fan in a closed-off enclosure. It is advised that the fan be installed at least 25 millimeters from the heat exchanger's edge. With this separation, the air exiting the fan has had time to "straighten," and the flow is uniform. Another crucial point to keep in mind is that the fan should be set up for air suction. This method has numerous important benefits, including:
Because more air is going through the heat exchanger, it performs better.
There will be significantly less noise.
The air outside the system, which is at the ambient temperature the system was designed for, will be used to ensure air flow, NOT the air inside the system, which is warmer than the ambient temperature. We must measure the difference in temperature between the inside and outside air, and we must ensure that we can still remove the necessary quantity of heat, if we do use the air inside the system and let it pass through our heat exchanger. If using air from the system is the only option, we must make sure there are enough ventilation openings to let the most fresh air, at or near ambient temperature, into the system. Also, we must ensure that there are no obstructions to the air movement to or from the heat exchanger.
Equally crucial is the position of the heat exchanger. To optimize the suction of outside air via the heat exchanger, we advise installing the heat exchanger near the system's edge and the fan inside in suction mode.
In order to fully empty the heat exchanger of ALL fluids, if necessary, it is crucial to place the heat exchanger with the fluid holes (both in and out) facing the bottom. The system may be under extremely low temperatures (as low as -20° C) during transit. If any fluid was left inside the heat exchanger when the system was exposed to such extreme temperatures for a number of days, the fluid would freeze and could shatter the tubing, which would result in a leak when the system was turned on.
It is suggested that the thermal calculation come first. To achieve the greatest outcome, it is advised to use a variety of working settings, including harsh ones. In order to construct the ideal heat exchanger with the best (gold) cost-benefit ratio, the best thermal calculation must be used first, followed by the mechanical one.
The performance of the overall system will be directly impacted by the difficult task of designing a heat exchanger. Several factors and variables must be taken into account, and if we do, we will have a reliable and effective system that uses the best heat exchanger while taking the cost-benefit analysis into account (while retaining the system's dependability and effectiveness).
Our professionals at Vrcoolertech are equipped and waiting to assist you with any heat exchanger need you may have. On our website, you may get more details.
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