THERMAL CONDUCTIVITY PREDICTION FOR FOODSTUFFS: EFFECT OF MOISTURE CONTENT AND TEMPERATURE

Figures & data

Table. 1. Mathematical Model for Calculating Thermal Conductivity as a function of Moisture and Temperature

Effect of Moisture and Temperature onThermal Conductivity
Proposal Model
where	λ=thermal conductivity (W/mK),
	X=the material moisture content (kg/kg db),
	T=the material temperature (°C),
	T r =a reference temperature T r =60°C, and
	R=0.0083143 kJ/mol K the ideal gas constant.
Adjustable Model Parameters
1.	λ o (W/mK): conductivity at moisture X=0 and temperature T=Tr
2.	λ i (W/mK): conductivity at moisture X=∞ and temperature T=Tr
3.	E o (kJ/mol): Activation Energy for heat conduction in dry material at X=0
4.	E i (kJ/mol): Activation Energy for heat conduction in wet material at X=∞

Table 2. Parameter Estimates of the Model Presented in Table 1

Material	n of Paper	nof Dat	λ (W/mK)	λ (W/mK)	E(kJ/mol)	E (kJ/mol)	T min (°C)	T ma (°C)	X min  (kg/kg db)	X ma (kg/kg db)	sd %
Cereal Products
Corn	1	1.58	0.07	7	5	10	7	0.0	8	5
Fruits
Apple	1	6	0.58	0.28	2	11	−40	9	0.1	19	11
Orange	1	0.64	0.10	1	0	1	6	0.6	19	1
Pear	1	0.65	0.27	2	1	15	8	0.5	7	2
Model Foods
Amioca	2	0.71	0.12	3	14	20	15	0.0	20	4
Starch	2	0.62	0.24	0	0	−42	12	0.0	24	1
Hylon	2	2	0.80	0.18	9	20	15	0.0	20	7
Vegetables
Potato	1	3	0.61	0.04	0	47	−15	13	0.1	7	6
Tomato	2	0.68	0.22	0	5	20	15	0.3	19	5
Diary
Milk	3	0.66	0.21	1	1	10	7	0.0	8	1
Meat
Beef	3	0.56	0.28	2	3	−30	9	0.0	3	2
Others
Rapeseed	3	0.23	0.08	3	0	−26	3	0.0	0	2
Baked Products
Dough	1	0.80	0.27	2	0	20	15	0.0	1	18

Figure 1. Parameter estimates of the proposed model of Table 1.

Figure 2. Thermal conductivity data for starch.

Figure 3. Thermal conductivity data for apple.

Figure 4. Thermal conductivity data for potato.

Figure 5. Predicted thermal conductivity values for fruits at 25°C.

Figure 6. Predicted thermal conductivity values for fruits at 60°C.

Figure 7. Predicted thermal conductivity values for vegetables at 25°C.

Figure 8. Predicted thermal conductivity values for vegetables at 60°C.

Figure 9. Predicted thermal conductivity values for miscellaneous foods at 25°C.

Figure 10. Predicted thermal conductivity values for miscellaneous foods at 60°C.