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Phase change materials (PCM)
have intensively been investigated for the last
20 years (1). Thermal energy storage is the main
application of these materials. The latent
energy, stored or released in the transition
stage of one phase to the other, is the
mechanism behind the improved storage ability.
Organic and inorganic substances function as
phase change materials, wax and paraffin are the
most prominent among these.
Heat application is a
traditional treatment approach for rheumatic
diseases. A variety of materials have been used
for heat packs which store heat inside the
package and conduct thermal energy to the body
region affected by rheumatic pain. Mud packs and
a mixture of inorganic substances, named fango,
with paraffin are widely used in Central Europe
for heat treatment. The time course of the
surface temperature of a variety of hot packs
have been reported (2,3,4, 5). However,
information on the mean temperature of the total
surface of these packs is rare.
The manufacturer of a newly
designed heat pack containing PCM claimed that
this new pack maintains a surface temperature of
52°C for 60 minutes when the package was stored
at 70°C for hours in a heating case prior to
application. The aim of this study was to
determine the surface temperature of the pack,
named Spitznertherm; and to compare it with the
surface temperature of a traditional parafango
pack.
The time course of the
surface temperature of two packs was determined. Measurements were performed
in a temperature controlled room at 24 ± 1 °C
using the Infrared scanner NEC San-ei
Thermotracer TH1104. The distance between the
pack and the infrared camera was approximately
170cm. The packs were placed on a woollen
blanket in order to minimise heat loss by
conduction to the ground.
The following packs were investigated:
3.1. Spitznertherm ®
This pack contains heat
powder PCM 127F/OG, with the main components
being fully refined paraffin with a melting
point of 52°C and silica. The powder is inside a
woven fabric envelope made of synthetic fibres.
The size is 50 by 70 cm, weight 2500 g. Prior to
application, the pack must be stored in an
heated oven for at least 4 hours. Measurements of two thermal
conditions were performed. In one case the pack
have been stored at 55°C and in the other case
at the recommended temperature of 70°C.
3.2 Perozon ® Fango-Parafffin
F
1000 g of Perozon Fango-Parafffin F contain 430g
natural fango powder and paraffin.The parafango pack was stored at 55°C prior to
the measurement. The size was 45 by 65 cm,
weight approximately 2000g.
4.1.Spitznertherm 55°C
The maximum temperatures recorded at the
start, 20 and 30 minutes later were 41.1°C,
36.7°C and 34.4°C respectively. At these
measurement times, the mean temperature of the
pack was 36.9 °C; 31.6°C and 30.4°C
The following diagram shows the course of
temperatures for 149 minutes.
4.2 Spitznertherm 70°C
At the start, 20 and 32 minutes later,
maximum temperatures were 45.1°C , 39.3°C and
39.1°C respectively. At these measurement times,
the mean temperature of the pack was 40.4°C;
35.6°C and 35.3°C
The following diagram shows the course of
temperatures for 112 minutes.
4.3.Parafango 55°C
At the start, 21 and 31
minutes later, maximum temperatures were 49.1°C,
44.0°C and 43.5°C respectively. At these
measurement times, the mean temperature of the
pack was 47.2 °C; 42.6°C and 40.3°C.
The following diagram shows
the course of temperatures for 116 minutes.
No difference was found in
the decrease of surface temperature between both
the packs investigated. The mean temperature
dropped by 5°C within 20 minutes. However, the
mean temperature of the parafango pack at the
start was 47.2° C, but for Spitznertherm stored
at 55°C only 36, 9°C and after storage at 70° C,
40.4°C.
The reason for this
differences might be that parafango packs
underwent a full melting process at 80°C prior
to the storage period of the pack in the oven at
55°C. During this melting process the parafango
accumulates extra heat. A similar mechanism is
intended when Spitznertherm is heated up to
70°C. However, with the available heating
equipment the heat accumulation might have
become insufficient resulting in lower surface
temperatures than traditional parafango packs.
[1] Zalba B, Marin JM, Cabeza
LF, Mehling H. Review on thermal energy
storage with phase change: materials, heat
transfer analysis and applications. Applied
Thermal Engineering 2003; 23: 251-283
[2] Matera R. Vergleichende
Messung verschiedener Fangoparaffin-Packungen.
Physiotherapie (Lübeck) 1976; 67:391-392, 398
[3] Kleinschmid J, Schnizer W.
Experimentelle Untersuchungen zu thermischen
Vorgängen bei der Anwendung von Heißpackungen.
Physiotherapie (Lübeck) 1980; 71(2):95-98
[4] Ammer K, Schartelmüller T,
Hauttemperatur nach der Anwendung von
Wärmepackungen und nach Infrarot-A-Bestrahlung.
Thermologie Österreich 1993; 3(1):51-57
[5] Ammer K. Wärmeverhalten
einer neuen Wärmepackung- Thermologie
Österreich 1995; 5(2): 60-64 |
