Characterization of Two Fumarate based MOFs for Water based Adsorption Heat Pumps
Tahmid Hasan Rupam1,2, Mujib L. Palash3, Bidyut Baran Saha1,2,4
1. Kyushu University Program for Leading Graduate School, Green Asia Education Center, Kasuga-koen6-1, Kasuga-shi, Fukuoka 816-8580, Japan
2. International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
3.Electrical and Electronic Engineering Department, University of Dhaka, Nilkhet Rd, Dhaka 1000, Bangladesh
4. Mechanical Engineering Department, Kyushu University, 744 Motooka, Nishi-ku,Fukuoka 819-0395, Japan

2. Adsorption chiller and the Mathematical models

1. Introduction
Thermodynamic compatibility is one of the major

Adsorption enthalpy

issues associated with the realization of a commercial

 P2 T1T2
Qst = Rln  
T2 − T1  P1 

MOF/water paired adsorption cooling system. This
study provides a comparative analysis of water
adsorption characteristics on two fumarate based

Coefficient of performance

metal organic frameworks- Aluminum fumarate andMOF801intermsoftheir

thermodynamic

COPth =performance indicators (theoretical coefficient ofperformance and specific cooling effect). Both theh fg (T , )Qst (T , )Specific cooling effect

MOFs showed improved performance than that ofcommonly used silica gel/water based adsorption

Tcond

SCE = (Wads − Wdes ) h fg (Tevap ) −  dh f Tevap


systems. This information along with the adsorption
isotherms and kinetics find immense importance in thedesign of an adsorption chiller.

3. Results and Discussion
3.1 Synthesis of MOFs

3.4 Water adsorption characterisitcs➢ PXRD in Fig. 1 ensured the successful synthesis of the MOFs

Fig. 1➢ Fig. 2 shows the FESEM images of the two studied samples. Micro domain sizes ofFig. 4Aluminum fumarate are irregular whereas, in case of MOF 801 they are spherical.
➢ Fig. 3 shows their pore size distributions, from where it can be concluded that thesamples are microporous.

3.2 Morphological properties of MOFs

3.5 Coefficient of performanceFig. 5Fig. 2Aluminum fumarate

MOF 801MIL 100 (Fe)

3.3 Porous properties

3.6 Specific cooling effectFig. 3Fig. 6➢ The s-shaped water adsorption isotherms (in Fig. 4) on MOFs enabled them to have ahigher net uptake (difference between adsorption and desorption uptake) than theconventional silica gel (RD type)➢ Fig. 5 and 6. illustrates significant improvement of the performance indicators forboth the studied MOF/water based systems over the silica gel/water based systems.

N.B. For Fig. 5 and 6, Cooling temperature was considered as 283K while having 343K as
desorption temperature.

5. References and acknowledgements

4. Conclusions
Incorporation of MOFs can bring the next revolutionary advancement in adsorption chillers.
MOF 801 stands out as one of the most efficient adsorbents to this date for the practical
adsorption chiller because of its having a lower release temperature and higher net uptake
along with its hydrothermal stability. The SCE and COPth for both the MOFs/water pair was
found higher than the silica gel/water pair. Further improvements can take place in the MOFs
to increase the uptake capacity and sorption kinetics.

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