Numerical Investigation of the ThermalEfficiency of a Sorption Compressor

A. Davidesko and N. Tzabar

Department of Mechanical Engineering, Ariel UniversityAriel 40700, Israel

ABSTRACT

Sorption compressors are thermally driven and do not have moving parts; therefore, they have

attractive for space missions. In comparison to a mechanical compressor, a sorption compressor has

INTRODUCTION

sorption cells.

may consist of different materials and dimensions. The model allows the applcation of different

Cryocoolers 20, edited by S.D. Miller, R.G. Ross, Jr. and J.R. Raab©¶International Cryocooler Conference, Inc., Boulder, CO, 2018 329

METHOD

transfer problem as one dimensional, in the radial direction. The sorption cell consists of several

model allows changing all dimensions, and it is possible to eliminate any material by applying

Finite differences method

by MATLAB code. Every material is divided into elements with a single node at the middle of rm(i), where i

cp k, and density, . In addition, each element has an internal heat generation parameter, qgen

(1)

where Rm+ Rm

- is a thermal resistor r

is an interval of rotation, and LThe second type of a thermal resistor is between different materials. In this case, the total

(3)

(4)

Sorption compressor general view

330 J - T AND SORPTION CRYOCOOLER DEVELOPMENTS

where Rm+contact Rm-contact is a thermal

(5)

where A hc is the convective heat transfer

(6) where lg Ac Av is the

kfC(i)

(8)

where henv Aout of the sorption cell.

where E Tielement i n

A general description of an element

Thermal resistance between two elements of different materials

THERMAL EFFICIENCY OF A SORPTION COMPRESSOR 331

The energy balance of element i

(10)

where qgen mj i at time step n+1

n

(11)

(12)

. The heat provided by the heater is implemented by qgen

(13)

where Ti0 i, Pin Ns

(14)

layer of, and 4 for the cell envelope. N

(15)

hroom Too is the ambient tem-Tout

332 J - T AND SORPTION CRYOCOOLER DEVELOPMENTS

MODEL VALIDATION

2 12

1

5

(16)

THERMAL EFFICIENCY OF A SORPTION COMPRESSOR 333

RESULTS & DISCUSSION

wminimum

where Pmax rin

y -

i i+1

334 J - T AND SORPTION CRYOCOOLER DEVELOPMENTS

Property M5

cp 1000 500 500450

ITESCHeater 1

Heater 4Heater 5

Different heaters dimensions

Material properties

Heater nameHeater 1 0 1

4Heater 4Heater 5

THERMAL EFFICIENCY OF A SORPTION COMPRESSOR 335

where Vi Vs

the sorption cell thermal design.

CONCLUSIONS

ACKNOWLEDGMENT

REFERENCES

Heat and Mass Transfer

Adv. in Cryogenic Engi-neering

-Adv. in Cryogenic Engineering

Heat Transfer

336 J - T AND SORPTION CRYOCOOLER DEVELOPMENTS