Adsorption Beds: The Significance of Thermodynamic Properties and Particle Size on System-Level Heat Pump Performance

2021 ◽  
pp. 1-42
Author(s):  
Bachir El Fil ◽  
Alexander Raymond ◽  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Low Cost ◽  
Particle Diameter ◽  
Water System ◽  
Packed Bed ◽  
System Level ◽  
Diffusion Resistance ◽  
Adsorption Heat Pump ◽  
Adsorbent Particle

Abstract The performance of an adsorption heat pump is a function of the equilibrium uptake and diffusion resistances of a particular system, which determine the refrigerant throughput during a cycle. Previous studies have sought improved sorption bed performance by increasing heat transfer; however, some of the proposed heat exchanger enhancements represent costly alterations to the system. This work instead investigates a method for optimizing sorption bed mass transfer, which can be implemented as a low-cost alternative to heat transfer enhancement or in addition to it. The objective is to balance the intra-particle diffusion resistance, which increases with adsorbent particle diameter, with the inter-particle pressure drop, which decreases with adsorbent particle diameter. A silica gel-water system model is used to show that the optimal particle geometry in a packed bed yields a 48% improvement in cooling duty and over 50% increase in COP compared with larger particles (dp = 1.42 mm).

scholarly journals Heat Transfer Accompanied by Adsorption/Desorption of Water Vapour in Adsorption Heat Pump of Packed Bed Type.

1993 ◽  
Vol 19 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Fujio Watanabe ◽  
Yoshito Watabe ◽  
Hitoshi Katsuyama ◽  
Jun Kozuka ◽  
Masanobu Hasatani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Water Vapour ◽  
Heat Pump ◽  
Packed Bed ◽  
Adsorption Heat ◽  
Adsorption Heat Pump ◽  
Adsorption Desorption

An Experimental Investigation on Forced Convection Heat Transfer From a Cylinder Embedded in a Packed Bed

1994 ◽  
Vol 116 (1) ◽  
pp. 73-80 ◽  
Author(s):  
K. Nasr ◽  
S. Ramadhyani ◽  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Particle Diameter ◽  
Packed Bed ◽  
Spherical Particles ◽  
Theoretical Equation ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

Forced convection heat transfer from a cylinder embedded in a packed bed of spherical particles was studied experimentally. With air as the working fluid, the effects of particle diameter and particle thermal conductivity were examined for a wide range of thermal conductivities (from 200 W/m K for aluminum to 0.23 W/m K for nylon) and three nominal particle sizes (3 mm, 6 mm, and 13 mm). In the presence of particles, the measured convective heat transfer coefficient was up to seven times higher than that for a bare tube in crossflow. It was found that higher heat transfer coefficients were obtained with smaller particles and higher thermal conductivity packing materials. The experimental data were compared against the predictions of a theory based on Darcy’s law and the boundary layer approximations. While the theoretical equation was moderately successful at predicting the data, improved correlating equations were developed by modifying the form of the theoretical equation to account better for particle diameter and conductivity variations.

scholarly journals Convection Heat Transfer Analysis in A Vertical Porous Tube

2020 ◽  
Vol 8 (1) ◽  
pp. 31-45
Author(s):  
Hikmat N. Abdulkareem ◽  
Kifah H. Hilal
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convection Heat Transfer ◽  
Particle Diameter ◽  
Vertical Channel ◽  
Packed Bed ◽  
Constant Heat Flux ◽  
Heat Transfer Analysis ◽  
Constant Heat ◽  
Flux Boundary Condition

Forced convective heat transfer in a vertical channel symmetrically heated with a constant heat flux, and packed with saturated porous media, has been investigated experimentally in the present work. The channel was padded with spherical glass of three diameter (1, 3 and 10 mm) in a range 0.0416 < (particle diameter / inner channel radius) <0.416. The experimental setup, using a copper tube as a packed bed assembly with (48 mm) inside diameter and (1150 mm) heated length with a constant heat flux boundary condition. The test section was vertically oriented with water flowing against gravity and packed with glass spheres (1, 3 and 10 mm) diameter respectively. The results show that local Nusselt number increased at 34% with increasing Reynolds number at 65% while increased at 11% with increasing heat flux at 71%. Heat transfer rate increase as the particle diameter increase at the range of (1 – 3) mm but decrease with increasing particle diameter at the range (3 – 10) mm. Pressure drop through channel minimize at 97% as porosity increase at 23%.Many empirical relations, obtained experimentally.

scholarly journals Thermal Performance of Heat Exchanger Using Zeolite/vapour Adsorption

2021 ◽  
Vol 333 ◽  
pp. 03006
Author(s):  
Soichiro Ohno ◽  
Shuji Hironaka ◽  
Jun Fukai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Balance ◽  
Flow Direction ◽  
Packed Bed ◽  
Maximum Temperature ◽  
Sensible Heat ◽  
Humid Air ◽  
Adsorption Heat Pump ◽  
The Heat Balance

About 60% of the energy input in the chemical industry is discarded from the plant. Energy saving can be achieved in the entire plant by recovering these waste heats and reusing them as power and heat sources in the power plant. An adsorption heat pump has been developed for the purpose of regeneration of such unused energy. In this study, saturated humid air was supplied to a device packed with 13X zeolite particles of 4 mm in diameter. The time variation of temperature in the apparatus was measured experimentally. Then, the maximum temperature was estimated from the relationship between heat balance and adsorption equilibrium. The trend of the maximum temperature calculated from the heat balance is consistent with experiment. Further, it was found from the result of the heat balance equation that the sensible heat of the humid air supplied and the heat of adsorption of the zeolite are mainly distributed to the sensible heat of the zeolite. In the future, it is important to make effective use of the sensible heat of this zeolite. In order to extract more thermal energy from the device, it is necessary to improve the heat transfer between the packed bed and medium. A double pipe heat exchanger having a zeolite packed bed on the annular side was proposed as an apparatus. Flow direction of the humid air supplied to device was changed in two different ways. The one of them is supplying humid air radial flowly to the device and another is supplying the air in parallel flow. The influence of flow direction on heat transfer between packed bed and medium is studied with numerical simulation.

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