Sunday, 10 November 2024
Mann-Kwi Park, Chairman, Jehin Solar, in this interview he gave to Surendar Balakrishnan in February 2020, expresses his keenness in introducing his thermal- driven solar cooling system with heat pump technology to supply ‘block cooling’ in the GCC region. Excerpts…
Mann-Kwi Park, Chairman, Jehin Solar, in this interview he gave to Surendar Balakrishnan in February 2020, expresses his keenness in introducing his thermal- driven solar cooling system with heat pump technology to supply ‘block cooling’ in the GCC region. Excerpts…
COULD YOU PLEASE DESCRIBE THE TECHNOLOGY YOU SPEAK OF?
My technology is basically a thermal-driven cooling system, not a vapour-compression cooling system. It uses solar energy as the heat source for adsorption chillers, not absorption.
Many people have tried to use absorption, but I believe there are limitations when applied with solar energy. Absorption works in higher temperatures, sometimes 100 degrees, sometimes 120 degrees. In the case of solar energy, the efficiency is low with high temperatures, hence I chose adsorption, which can start working at relatively low temperatures. My chiller – the jChiller, is adsorption-based and starts working from 55 degrees C. The solar collectors in the system make 55 degrees C and go up to 70 or 80 degrees C, which is fine – at 60 degrees C, the efficiency goes up to 65%.
I have had a background in solar thermal since 1983. About 15 years ago, with the help of the Korean government’s R&D grant, I developed a mega collector, which is 2 x 5 metres. A normal-sized solar collector, as you would know, is 1 x 2 metres. I finished developing the mega collector in 2008. The original target for the technology was district heating application in Korea, though it is very ideal for district cooling, as well. And compared to a traditional solar collector, which needs 12 collection points in a 10-square-metre field, my mega collector just needs two. It is maintenance-free, and there is no worry about leakage at any time.
My technology is ideal even in intermittency. I mean, what do you do when you use solar energy as heat source for adsorption cooling, and that there is inadequate solar radiation, or on some days, it is cloudy and rainy. With this question in mind, I engaged the geothermal heat pump technology, on which I have been working since 1998. So, in a nutshell, my system is a combination of heat pump with adsorption chiller as a hybrid; that way, I am able to minimise the solar field for the adsorption chiller. I am able to cover the day and night intermittency with a small space and small storage tank.
Now, a normal, traditional heat pump can produce just 7 degrees C cold water from the evaporator and 55-60 degrees of hot water from the condenser side.My jChiller can produce from 55 degrees C, but the point was that if we supplied 60 degrees C, the efficiency of the jChiller was lower. I solved this problem by reasoning that if I make the heat pump cascade to variable compression – the first level being R-134a and the second level being R-410a – I would be able to heat up to 90 degrees C very easily. Through adopting this approach, my heat pump is able to produce 7 degrees C of cold water and 80-90 degrees C of hot water at the same time. The hot water, at 90 degrees C, will go through the jChiller and produce cold water for space cooling. Meanwhile, the heat pump can produce 7 degrees C of cold water. Combined, I am able to supply for space cooling. Now, typically, while I can produce 7 degrees C of cold water through the heat pump, it is obvious that it depends on the outdoor temperature, and that way, the COP will be 3 or, maximum, 3.5. In hot areas, like here in the GCC region, the COP might be less than even 3. With my system, it is possible to produce at the cold side with a COP of 3.5, and at the hot side with a COP of more than 3.5. So, the total combined COP will be more than 7. This is the basic reasoning behind developing the hybrid system,consisting of a solar thermal-driven jChiller and heat pump.
WHAT IS THE CAPACITY OF YOUR SYSTEM?
At the moment, I have four standard models – 20, 30, 40 and 50. Our standard model is the SC-50, with SC denoting Refrigerated Tonne (RT). So SC-50 is a 50 RT system.
AND ARE YOU ABLE TO RAMP IT UP BY ADDING MORE MODULES?
Yes, in serial. I can combine five modules to give 250 RT.
SO, THE STANDARD MODEL OF THE JCHILLER IS ABLE TO PROVIDE 50 RT AT ITS PEAK. WHAT KIND OF APPLICATIONS ARE YOU LOOKING AT IN THIS REGION?
I developed the system in Korea, where we need approximately 60 days of cooling in a year. Here in the GCC region, on the other hand, you need 10 months or approximately 300 days of cooling a year. This is one reason I have come here. This is my target area. Also, my system uses solar radiation as a heat source. The annual average of solar radiation in Korea is 4.2 kW per square metre per day, whereas here, it is 6.4 kW per square metre per day. It is nearly 1.5 times more here, which makes it the perfect area for my technology.
To answer your specific question on where it can go into, the system can go anywhere that a normal air conditioner can go. It is not designed for an individual villa, but it is designed for clusters of villas. So, it is ideal for ‘block cooling’, as opposed to District Cooling, which in Korea is cooling a city. And so, the technology is designed for any form of space cooling right up to district cooling.
And the fact that the largest chiller is only 50 RT has no effect at all on the efficiency of the system, when you consider it is essentially a box with a phase-change material inside. In other words, building a bigger one isn’t going to save any money.
In terms of applications, at the moment, I want to concentrate on some commercial buildings. The second stage of my application would be block cooling.
HOW DO YOU COMPARE WITH OTHER SYSTEMS IN THE MARKET, COST-WISE?
At the moment, I am working with people on a large villa application, two factories, a government centre and a number of indoor farming facilities here in the UAE. The technology seems to have found a niche in indoor farming, and the reason for that is that in an indoor farm, 40% of its cost is cooling. I can eliminate almost all of that cost, because as a general rule, the setpoints in an indoor farming environment range from 25 degrees C to 28 degrees C, or from 23 to 28. There are periods of time when certain crops have to be cooler, but not overall. And so, being able to remove 40% of the operational cost of an indoor farm makes it viable, because at the moment, you grow fruit and vegetables at a higher cost than the normal price, and that’s a niche market. Make it cheaper than the normal price, and you are going to get real traction. So, that’s a major area I am involved in.
And then to get on to your second point on the cost, at the moment, everything is being made by hand, but I have been doing projections on mass production, and the intent is to be manufacturing in the UAE by April or May. At that time, the cost of the equipment will be roughly 60% more than a traditional air conditioner, and depending on the cost of power, you are going to get a payback somewhere between two-and-a-half and three-and-a-half years, if you are using the air conditioning over time. If you are note, then it will be longer, of course. But that’s a payback – you have got your money back, and after that, it’s free.
The equipment is expected to have a life of 30-40 years, so you are not going to have to be replacing it every 12-15 years, as well. So it is a very
good economic picture, and on the maintenance side, there is no scheduled maintenance at all for the chiller or for the heat pump. It has circulation pumps that require normal maintenance, but on the chillers, it is just closed pumps. And of course, the solar equipment cleaning involves costs, but nowhere near the same level as solar PV, because we are not trying to generate electricity, we
are capturing heat, and heat can get through a slightly dirtier surface.
COULD YOU DESCRIBE YOUR SOLAR COLLECTORS?
If your imagination can extend to 2 x 5 metres, that’s the size. My system has three major pars. First of all, there are the solar collectors. At the moment, in the international market, a 1 x 2 metre solar collector would cost USD 200. That’s the international market price. The second part is the heat pump, and the third part is the adsorption chiller. As I earlier said, it is a hybrid system. Our cost is very high at the moment – maybe USD 6,000 per RT.
USD 6,000 PER RT? WOW!
Yes, wow! So, at the moment, we are considering moving our factory to here in the UAE, because I believe our market is in the sunbelt area. The UAE is at the centre of the sunbelt, so there is more reason to move from Korea to here.
With the purpose of setting up the factory here, I established our company in the UAE last year – on December 22, 2019, to be specific – in KIZAD, in Abu Dhabi. And now,
I will introduce automation and local labour. The target is to bring the price down to USD 3,900 per RT
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