This research work was sponsored by the National Key Basic Research Program of China (No.2015CB251303), and the National Natural Science Foundation of China (No. 51276005).

1. Experimental Setup
NOTE: The adsorption refrigeration system was composed of the adsorption bed, the evaporator, the condenser, the vacuum pump, and the solar trough collector (Figure 1). An automatic solar tracking device with a parabolic trough was manufactured and applied in the system to improve the efficiency of the solar collector. The automatic solar tracking trough was driven by the worm-gear device as shown in Figure 2. The ...

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I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorptive+air+conditioning+systems+driven+by+low+temperature+energy+sources:+choice+of+the+working+pairs.">Adsorptive air conditioning systems driven by low temperature energy sources: choice of the working pairs.</a> J Chem Eng Jpn. 40 (13), 1287-1291 (2007).</li><li>Kakiuchi, H., Shimooka, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+vapor+adsorbent+FAM-Z02+and+its+applicability+to+adsorption+heat+pump.">Water vapor adsorbent FAM-Z02 and its applicability to adsorption heat pump.</a> Kagaku Kogaku Ronbun, Jpn. 31 (4), 273-277 (2005).</li><li>Li, X. H., Hou, X. H., Zhang, X., Yuan, Z. 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The authors have nothing to disclose.

As a thermodynamic system, the performance of a solar adsorption refrigeration device depends on the optimum design and the proper operation of the system. Both the heat supply and the cooling method of the bed are important to guarantee the system works well. Water cooling is preferred to air cooling because of the high strength of convection heat transfer of water. The poor conductivity of the adsorbent material has usually determined the limited heat transfer rate of the bed. To improve the heat transfer of the bed, m...

With the ozone-depletion problem of traditional vapor compressed refrigeration growing more serious, substituting traditional refrigeration with green technology has become a hot topic in recent years. Among those green technologies, the solar adsorption refrigeration has attracted much of the attention of researchers. Driven by low-grade thermal energy, the adsorption refrigeration system has the advantages of being environmentally friendly, small, and flexible. This adsorption system can also be driven with non-solar energy, for instance by waste heat discharged from thermal equipment or by engine exhaust gases from vehicles, as mentioned by Hu et al.1
In an adsorption cooling system, the adsorption bed is the key component. Its work directly affects the performance of the whole system. Therefore, the design of the adsorption bed is the most important issue as pointed out by Sutuki.2 A decade ago, the flat bed was mostly used in the adsorption cooling system.3,4,5 Without any solar concentrating device, the flat bed temperature was usually low and hence the COP of the system was unsatisfactory. In contrast, the tubular adsorption bed improved the COP. It was reported that the COP could reach 0.21 in sub-Sahara region by Hadj Ammar et al.6 Furthermore, Wang et al.7 developed a spiral plate adsorber that was distinguished by the characteristic of continuous heat regeneration. The novel design of the adsorption bed shortened the cycle time of the system. Abu-Hamdeh&#160;et al.8 reported their study on the solar adsorption refrigeration system with a parabolic trough collector. Their test results showed the COP of the system varied from 0.18 to 0.20. El Fadar et al.9 studied an adsorption refrigeration system that was coupled with a heat pipe and powered by parabolic trough collector, which showed an optimum COP of 0.18.
To enhance the heat transfer of the tubular bed, some finned tube adsorbers were considered and the effect of the enhancement was examined. An innovative bed that took the form of the shell and tube heat exchanger was presented by Restuccia et al.10. The internal finned tube was coated with a zeolite layer so that the contact transfer resistance of heat/mass between the metal surface and the adsorbent material could be reduced. The system produced an output of 30-60 W/kg of specific cooling power in the cycling time of 15-20 s. Al Mers et al.11demonstrated that the enhanced adsorber with 5-6 fins could significantly reduce the heat loss of the adsorber to ambiance and thereby improving the COP by 45%. The effect of a finned tube adsorber on the performance of the solar driven system was also studied by Louajari et al.12. Using activated carbon-ammonia as the working pair, they showed that the cycling mass transfer in the adsorber with fins was greater than the one without fins.
In the current study, we experimentally studied an improved solar adsorption refrigeration system, in which a solar tracking parabolic trough collector was applied and an internal cooling tunnel was deployed. With the SAPO-34/ZSM-5 zeolite and the water vapor as the working pair, the system showed interesting characteristics in terms of thermodynamics and refrigeration. The experimental methodology as well as the typical test results will be presented and discussed in this report.

<table>
	<tbody>
		<tr>
			<td>evaporator</td>
			<td>home-made</td>
			<td></td>
			<td>finned heat exchange</td>
		</tr>
		<tr>
			<td>condenser</td>
			<td>home-made</td>
			<td></td>
			<td>finned heat exchange</td>
		</tr>
		<tr>
			<td>evaporator water tank</td>
			<td>home-made</td>
			<td></td>
			<td>volume:9L</td>
		</tr>
		<tr>
			<td>condenser water tank</td>
			<td>home-made</td>
			<td></td>
			<td>volume:9L</td>
		</tr>
		<tr>
			<td>vacuum pump</td>
			<td>Beijing Jing Rui Ze Xiang Instrument Co. Ltd.</td>
			<td></td>
			<td>rotation speed:1400 motor pover:370W</td>
		</tr>
		<tr>
			<td>condenser pressure sensor</td>
			<td>Beijing Li Nuo Tian Sheng Instrument Co. Ltd.</td>
			<td>16P2623</td>
			<td>maximum:2200Pa</td>
		</tr>
		<tr>
			<td>bed pressure sensor</td>
			<td>Beijing Li Nuo Tian Sheng Instrument Co. Ltd.</td>
			<td></td>
			<td>maximum:2200Pa</td>
		</tr>
		<tr>
			<td>adsorption bed</td>
			<td>home-made</td>
			<td></td>
			<td>cylundrical glass tube</td>
		</tr>
		<tr>
			<td>parabolic trough</td>
			<td>home-made</td>
			<td></td>
			<td>high reflective aluminum sheet</td>
		</tr>
		<tr>
			<td>water pump</td>
			<td>home-made</td>
			<td></td>
			<td>motor pover:250W, water head:8m</td>
		</tr>
		<tr>
			<td>water tank</td>
			<td>home-made</td>
			<td></td>
			<td>volume:500L</td>
		</tr>
		<tr>
			<td>DRT-2-2 direct solar actinometer</td>
			<td>Beijing Tian Yu De Technology Co. Ltd.</td>
			<td>03140132</td>
			<td>sensitivity:13.257&#956;V/W&#8226;m2</td>
		</tr>
		<tr>
			<td>TBQ-2 solar pyranometer</td>
			<td>Jinzhou Sunshine Technology Development Co., Ltd., China</td>
			<td>209079</td>
			<td>sensitivity:12.733&#956;V/W&#8226;m2</td>
		</tr>
		<tr>
			<td>SAPO-34 zeolite</td>
			<td>Langfang Peng Cai Co., Ltd., China</td>
			<td></td>
			<td>20mm in length and 2.2mm in diameter</td>
		</tr>
		<tr>
			<td>ZSM-5 zeolite</td>
			<td>Langfang Peng Cai Co., Ltd., China</td>
			<td></td>
			<td>5.7mm in diameter</td>
		</tr>
	</tbody>
</table>

experimental system of solar adsorption refrigeration with concentrated collector

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The main components of the system were the adsorbent bed, the condenser, the evaporator, the cooling sub-system, and the solar collector. In the first step of the experiment, the vapor-saturated bed was heated by the solar radiation under closed conditions, which caused the bed temperature and pressure to increase. When the bed pressure became high enough, the bed was switched to connect to the condenser, thus water vapor flowed continually from the bed to the condenser to be liquefied. Next, the bed needed to cool down after the desorption. In the solar-shielded condition, achieved by aluminum foil, the circulating water loop was opened to the bed. With the water continually circulating in the bed, the stored heat in the bed was took out and the bed pressure decreased accordingly. When the bed pressure dropped below the saturation pressure at the evaporation temperature, the valve to the evaporator was opened. A mass of water vapor rushed into the bed and was adsorbed by the zeolite material. With the massive vaporization of the water in the evaporator, the refrigeration effect was generated finally. The experimental result has revealed that both the COP (coefficient of the performance of the system) and the SCP (specific cooling power of the system) of the SAPO-34 zeolite was greater than that of the ZSM-5 zeolite, no matter whether the adsorption time was longer or shorter. The system of the SAPO-34 zeolite generated a maximum COP of 0.169.

Mass transfer characteristic of the bed through the adsorption process 
The adsorption bed is always the most important component in an adsorption refrigeration system, and the heat and mass transfer characteristic are the main factors affecting the performance of the whole system. By analyzing the recorded temperature change in the cross sections as shown in Figure 3(bottom panel),&#160;it is possible to know the heat and mass transfer ...

Watch this Scientific Journal Video about Experimental System of Solar Adsorption Refrigeration with Concentrated Collector at JoVE.com

Experimental System of Solar Adsorption Refrigeration with Concentrated Collector

With solar energy as the driving force, a novel adsorption refrigeration system has been developed and experimentally investigated. Water vapor and zeolite formed the working pair of the adsorption system. This manuscript describes the setup of the experimental rig, the operation procedure, and the important results.

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The ...

The overall goal of this experiment is to study the refrigeration performance of a solar adsorption system with a solar collector trough. This method can help answer key questions in the solar adsorption cooling field, such as how to improve the coefficient for performance and the specific cooling of the power of the system. We first had an idea for this method a few years ago, when we considered how to reduce the cooling environment by making use of solar energy.This is the solar adsorption refrigeration system on the campus of Beijing University of Technology. A principle component is an adsorption bed at the focus of a solar trough collector, with a solar tracking device. The bed is connected to a condenser and an evaporator.The evaporator is seated on a water tank that will be cooled by the system. A circulating water loop can cool the adsorption bed. The connections among these elements are in this schematic.The adsorption bed is connected to the evaporator and condenser by tubing. A pressure gage monitors the pressure in the adsorption bed tube. A valve can isolate the adsorption bed.To release water vapor from the adsorption bed, open this valve and the one at the condenser. Close the condenser valve and open the evaporator valve when it is time for the adsorption bed to take in water vapor. A pump establishes a vacuum in the tubing, connecting the bed evaporator and condenser.When necessary, the circulating water loop cools the adsorption bed. Details of the adsorption bed are in this schematic. There is an outer glass tube.It is concentric with the solar-adsorbing tube. Between the two is a vacuum. Inside the solar-adsorbing tube is a concentric copper tube for the water cooling system.This cross-section reveals that there is a mass-transfer channel off the central axis. The region between the solar-adsorbing tube and the interior tubes is packed with adsorbent material with water as the refrigerant. There are temperature probes in the adsorbent material at different points in the system.Two are 140 millimeters from one end of the system. Five are arrayed at the middle of the system. Two more are 140 millimeters from the other end of the system.To begin the cycle that results in refrigeration, start with the solar trough aligned to track the sun. Manually adjust the trough to maximize its exposure to the sun, then move to isolate the adsorption bed and ensure the pressure of the bed and the tube is below 800 pascals. Do this by shutting off the valve connected to it.Ensure that all valves are closed and that no cooling water circulates, then start the controller for the solar tracking system. Over time, the system tracks the sun, which heats the water-saturated adsorption bed under closed conditions. As the trough moves, monitor the bed pressure with the pressure gauge.Wait for a pressure above the value for the condensation temperature of the environment. At an appropriate pressure, start the desorption process. Open the valves that allow a connection between the bed and the condenser.As the water vapor flows, maintain solar heating to the adsorption bed. When the bed and condenser pressures are the same, turn off the valves between the bed and condenser. Next, obtain an aluminum foil sheet, enough to cover the adsorption bed.Use it to shield the tube from solar radiation, in order to start the adsorption process. Open the circulating water loop to cool the adsorbent material. Monitor the bed pressure to identify when it is below the evaporator's saturated vapor pressure.At that point, open the valves between the bed and the evaporator. Let the water vapor rush into the bed. Continue the adsorption process and record the change in bed temperature and bed pressure.When the bed and the evaporator have equal pressures, close the valves connecting the two. Then, stop the flow in the water loop. Finally, remove the aluminum foil block from over the adsorption tube to start the desorption process.These data are from the nine temperature sensors over the course of the adsorption process, using SAPO-34 zeolite. The plots are for sensors nearest to the evaporator, at the center of the rod, and furthest from the evaporator. Plotted together, the data demonstrates that adsorption at different sections starts at almost the same time.This suggests the mass-transfer ability of SAPO-34 is good. The water cooling system prevented temperatures from rising after about 400 to 600 seconds of adsorption, expect for at the far end of the tube. Different adsorption materials have different heat transfer properties.These data-compared temperatures of SAPO-34 zeolite in blue and ZSM-5 zeolite in red during desorption. Solar intensity data for the two different trials do not suggest a great difference in heating. Despite this, the temperature increase in the ZSM-5 zeolite was 32 degrees Celsius, while that in the SAPO-34 zeolite was 17 degrees Celsius.The ZSM-5 has better heat transfer characteristics in comparison with SAPO-34. Measurement of the evaporator chilled water tank temperature reveals the different adsorption materials have a performance difference. With the SAPO-34 zeolite, the temperature declined quickly and then slowed down.The temperature change with the ZSM-5 zeolite was relatively smooth throughout. The advantage of this technique is that maleficent coolant is chilled through the enhance of the transfer in the solar adsorption bed. So, this method provides insight into the solar adsorption techniques.It can also be a light into other systems, such as air conditioning. A master of this technique can be done into yours if it is performed properly. After you watch this video, you should have a good understanding of how to realize refrigeration, using only solar energy as the process.Don't forget that working with the adsorption bed at high temperatures can be extremely higher death and the precautions, such as maintaining your distance from the bed, should always be taken while performing the procedure.

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14.3K Views.  Beijing University of Technology. The overall goal of this experiment is to study the refrigeration performance of a solar adsorption system with a solar collector trough. This method can help answer key questions in the solar adsorption cooling field, such as how to improve the coefficient for performance and the specific cooling of the power of the system. We first had an idea for this method a few years ago, when we considered how to reduce the cooling environment by making use of solar energy.This is the solar adso...