Everything's relative: Renowed genius lends his weight to refrigeration system

Difficult as it may be to believe sometimes, the UK enjoys an average of 1,700 hours of sunshine every year! Helping companies to benefit from the potential of this free energy, SolarCool Energy has used that solar energy to pioneer the design of energy-saving solutions for businesses and retail outlets. Because commercial refrigeration is one of the largest consumers of electricity in the World, it isan industry sector that is of particular interest to the company. It is an application where it has worked hard to improve upon an original idea - to employ solar thermal collection as part of an air conditioning cooling system.

“The project began when we set out to improve on an existing solar thermodynamic solution,” said Roger, Sales Director at SolarCool Energy. “We were intrigued by the science behind the idea and believed that if we could get the system to work more effectively it could have huge potential in commercial refrigeration systems.” SolarCool’s Joint Managing Director in Germany is a thermodynamics professor and the Technical Director is a qualified refrigeration engineer, and so it made sense to bring these two disciplines together. Together their expertise turned a scientific theory, about the use of a solar thermal collection solution as part of a conventional refrigerant system, into a practical real life and viable commercial solution.

Four years of development work resulted in the introduction of a thermodynamic collection system that captures energy from the sun to heat refrigerant. When added to a standard refrigeration or air conditioning system this helps reduce the compressor workload, which, in a typical system, is where the refrigerant would be heated up and which is responsible for 80% of the total energy consumption of the system. In essence, the SolarCool thermal collection system was born out of the idea behind the original absorption refrigerator design - one of the lesser known inventions of none other than Albert Einstein and one of his students, Leo Szilard. Using the absorption process, Einstein and Szilard developed the first fully functional refrigerator with no moving parts. Their aim was to solve a problem with the mechanical compressors used in fridges in the early 1900s. At the time, they relied on poisonous gases as the refrigerant, which had a nasty habit of killing people on a regular basis. The absorption refrigeration technique requires a heat source - originally a natural gas flame - to drive the absorption process and release coolant from a chemical solution, in place of a mechanical compressor.

SolarCool’s thermal collection system uses this basic absorption principle, partnered with the refrigeration compression cycle, utilising solar energy as the heat source. Before explaining where the SolarCool system fits into an existing, conventional, system it is worthwhile explaining how a conventional refrigeration system works.

A typical refrigeration process comprises a continuous cycle that starts with gaseous refrigerant flowing through a compressor, where its temperature is raised. It then flows through a condenser, where it turns from being a heated vapour to a liquid, giving off heat in the process. The refrigerant is then forced through an expansion valve, where it experiences a rapid pressure drop. Finally, it moves to the evaporator, which causes it to vaporise, drawing heat from the area being cooled. The vaporised refrigerant then returns to the compressor and the cycle continues.

The SolarCool solution improves on this with the addition of a specially designed and patent pending process which uses natural ultraviolet radiance from the sun, or third-party waste heat, further heat the refrigerant gas. This process then reduces the strain on the compressor and less electricity is required. The hotter the refrigerant gets the more efficient the cooling system. It is possible to completely shut down a secondary-stage compressor, or slow down a variable speed compressor, without any adverse effect on system efficiency.

Discussing the challenges faced by the company when it introduced this revolutionary idea to the market, Roger explained that the biggest hurdle that they needed to overcome was to gain acceptance of the science behind the system. “Refrigeration engineers could not get their heads around the idea that the system is able to increase the temperature of the refrigerant without increasing pressure. To be fair, it goes against everything that they have been taught.” Basic physics teaches us that when you raise temperature you raise pressure equally. However, with SolarCool this is not the case. When their system heats the refrigerant, the kinetic energy is increased and the molecules space out and move more quickly. Because the gas enters the panel at a lower speed than it leaves, any pressure increase is dissipated by the increase in the velocity of the refrigerant as it travels to the condenser. This creates a strong Delta-T reaction, with the refrigerant gas being considerably more volatile and picking up the cooling process faster as a result.

Luckily, the company has now reached a point where it has overcome the initial mistrust of the science that underpins the SolarCool concept. “We now have plenty of data and evidence from real life applications, which show that the system is able to deliver some impressive energy savings. The likes of Cummings, Toyota, Hard Rock Resorts, Cable & Wireless and Intel can all testify to this. We are continuing to develop the system to allow it to work with a wider range of applications to allow us to help more companies save energy,” Roger concluded. So, it turns out that not only was Einstein a visionary in understanding energy, but his legacy is contributing to its conservation.

SolarCool Energy has worked with Breakthrough funding, a company that helps UK SMEs achieve R&D tax credits - a government scheme created to enhance and reward innovation amongst UK businesses. Could you be eligible? Click here to learn more.

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