Background

Medical and laboratory equipment often includes lasers which can become very hot during operation. A form of efficient cooling solution, which can be integrated directly into the equipment, to prevent overheating, shutdown, or permanent is a must.

“We are sorry, but we cannot deliver the cooling capacity on request due to space limitation”, similar statements have been heard from manufacturers of medical devices and another precise instruments over and over. However, the compact housing of such devices often does not provide enough space. To achieve the cooling effect, the only solution is to use larger housings.

The widespread thermoelectric technology(TE / Peltier technology) is relatively compact, but it has a high power draw. It consumes 4 to 6 times more power than equivalent miniatured compressor-based systems. This makes them very expensive to operate. Additionally, it only has a limited cooling effect which is dependent on the ambient temperature to make matters even more complicated. To reach the given cooling capacity, it has to be made in large and bulky structures, which is taking up too much space and costing too much.

Hence, the market required an alternative rather sooner than later. The space and performance restrictions have always been a problem for electronic device providers. Then, the unbelievably compact DC rotary compressor that is not bigger than a human fist comes out on the market. It’s the world’s smallest compressor. The mini-compressor is as powerful as any conventional available reciprocating compressor while also offering a considerably higher level of compactness, quiet operation, and low weight. Due to its numerous and compelling advantages, the small compressor was used to develop active cooling systems. The systems turn out to have a significantly smaller footprint and a higher level of compactness than traditional solutions.

With the increasing demand for small cooling solutions in the global market, today we’ve developed a lineup of models. They’re used in a wide range of electronic devices, precise instruments, and many other thermal management applications cooling where weight and space are crucial.

So far, vapor compression refrigeration and Peltier cooling are the only 2 technology options available to achieve ambient cooling for electronic enclosures and other precise devices. Therefore, for the device manufacturers,to develop the optimum cooling solutions for your applications, it is necessary to acknowledge the performance difference between these 2 technologies.

Performance Comparison

To fairly evaluate the size, weight efficiency, capacity, and relative cost of these micro vapor compression and Peltier technologies, we conducted thermal evaluation testing of our 24V DC vapor compression mini chiller unit MS02824E-P6 and a competing Peltier chiller with similar ratings. The MS02824E-P6 rated at 550 watts(temperature dependent), is a compact, reliable mini-compressor-based cooling system. The competing Peltier chiller is rated at 440 watts which is rugged performance. The evaluation methodology was to examine each product under the same environmental conditions, using the same thermal chamber. A series of performance data was generated using a common electric heat source to determine the cooling capacity and power consumed at various ambient temperatures. The consequences of these tests are presented below, and we can see the limitations of the Peltier cooler and the high energy efficiency of our cooling units.

According to table data, the vapor-compression chiller has a smaller footprint and weighs less than the TE cooler. The miniature compressor cooler provides a cooling capacity of 550W versus 303W for the TE cooler. The power of the compressor-based cooler consumed is less to cool the thermal load, 230W versus 721W.

The data clearly shows that the miniature compressor system has almost twice the cooling capacity of the TE cooler, and it is a significant advantage over thermoelectric cooling.

To fairly assess the characteristics of the micro-compressor refrigeration systems and the Peltier systems, and to select an optimum cooling solution, we need to normalize the characteristics for the desired cooling capacity required in the application. For instance, we normalized the characteristic for each 100 watts of cooling capacity and assessed their economic efficiency in a task scenario of cooling medical/laboratory equipment at a specific power rating.  The data in Table 2 presents the results of this normalized comparison.  Our miniaturized compressor systems are 3 times smaller, more than 4 times more efficient, and 5 times lighter than the Peltier systems.

Life Cycle Cost Comparison

After the comparison of size, power, and weight between the 2 technologies, let’s move on to the operating cost.  Many system integrators probably consider that the Peltier cooler technology has an advantage. But we must consider one factor, that’s the Peltier cooler is inherently 6 times less efficient than vapor-compression cooler. Also, we have to be concerned about the more significant power requirement of the Peltier systems.

From the data shown in Table 3, more than twice as many TE coolers are required to meet the same task requirement. The TE coolers are much heavier and larger compared to the MOIR compressor-based system. And more power is consumed than the compressor cooling unit.

Plus, the capital cost of the compressor cooling system is $550 in terms of normal capital costs. Its operating costs save around US$10,000 over 1,000 hours.

Conclusion

So, by the comparative testing, the significant advantages of compressor mini-cooling unit are obvious, in terms of size, weight, and power consumption in the same condition. The TE structure is simple and operates with less cost, and they can be ideal in certain situations where only small temperature differentials and low cooling capacity are required.  However, when considering the total cost and better cooling, especially for cooling requirements above 100 watts, the miniaturized compressor cooling system is a better choice.

What’s more, MOIR’s mini cooling units are powerful and robust and can operate in harsh and demanding environments, including extreme temperatures and combat conditions. They have proven their high durability and reliability for field operation( MTBF of over 90,000 hours).  It adopts a direct current inverter small compressor with R134a and R290 refrigerant which are environmentally friendly and safe for outstanding cooling performance.

In addition, thanks to its low-voltage technology, the necessary safety approvals for medical equipment applications can be obtained much more easily. Hence, it is very popular in the laser, medical equipment and laboratory fields as well as in numerous customer-specific thermal management applications.

After all, the future cooling system had to be not only particularly small but it also had to be exceptionally powerful, with a low noise level and a low level of vibrations. In addition, it also had to be extremely lightweight.  

If you need a compact refrigeration system for your medical equipment or other precision instrument cooling, please do not hesitate to contact info@moircooling.com.