IPC2012-90291

Proceedings of the 2012 9th International Pipeline Conference IPC2012 September 24-28, 2012, Calgary, Alberta, Canada

IPC2012-90291 Testing and Analysis of the Soil Thermal Conductivity in Tropical Desert and Grassland of West Africa Yutian Li

Changchun Wu

Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China Univ. of Petroleum-Beijing Beijing, China


Xiaokai Xing

Mingliang Yue

Yun Shang




ABSTRACT Thermal conductivity is one of the basic thermal properties of soil. For a buried pipeline, the thermal conductivity of the surrounding soil is the most important factor determining the overall heat transfer from the pipeline, and plays an important role in assessing the safety and energy consumption of pipeline operation. For providing reliable basic data for the commissioning and the operation of a waxy crude oil pipeline stretching in southwest Sahara Desert, six phases of thermal conductivity testing were performed along the pipeline route, respectively in February, March, April, May, July and September, 2011. The pipeline is 462.5km long and 323.9mm outside diameter. The pipeline route crosses tropical desert and grassland. Test points are located at roughly equal spaces along the pipeline route, and additional test points are located in seasonal river beds and rugged terrains. The soil temperature and thermal conductivity were tested simultaneously at a depth of about130cm below soil surface, which is also near to the pipeline centerline. The test equipment used was a field thermal needle system FTN01 for thermal conductivity made in Holland. For a given location along the pipeline route, the soil thermal conductivities have different values in dry season and rainy season. The average soil thermal conductivities for the pipeline route between two stations ranges from 0.5 to 1.1W/(m∙℃) in rainy season ， and from 0.4 to 0.8 W/(m∙℃) in dry season. The test results show that the change of soil moisture content has significant impact on soil thermal conductivity. Because other properties of the tested soil along

the pipeline route such as soil mineral composition, particle size distribution and density have no significant change, these factors have little effect on soil thermal conductivity. conductivity. Keyword: Thermal conductivity; Soil; Pipeline; M easurement;

NOMENCLATURE A Ei(x) Q R T T li N γ

λ

the thermal diffusivity, diffusivit y, in [m 2 /s] exponential integral function the heat power per unit length, in [W/m] the distance from one point to the line heat source the heating time, in [s] the temperature corresponding to the time t, in [ ℃] the distance between the point i and point i-1, in [km] the number of the testing points in the calculation area Euler gamma constant, 0.577 the soil thermal conductivity, in [W/(m∙℃)]

λ ave. ave. the average soil thermal conductivity, in [W/(m∙℃)] λ i

the soil thermal conductivity of point i, in [W/(m∙℃)]

w

the soil volumetric moisture content, in [V/V]

INTRODUCTION Soil thermal conductivity plays a critical role in the safe and economic operation of a hot oil pipeline. The values of soil thermal conductivity along the hot oil pipeline directly impact the overall heat transfer coefficients, and then the cooling rates of the fluid contained in the pipeline. [1] If only the soil thermal

conductivity distribution distribution along the pipeline well-established, all these factors can be properly determined, which include the number and the location of the heating stations to be built along the pipeline, the pipeline preheat and start-up, plan, reasonable heating temperature in the normal operation, and so on. Measuring the soil thermal conductivity along the pipeline can be difficult because of the long distance covered and complex terrain. At present many research on soil thermal conductivity is concentrated in some areas such as ground source heat pump, which is characterized by small test areas, large test depths, and fewer factors affecting the soil thermal conductivity. Studies on the soil thermal conductivity of pipeline route are insufficient and there is no systematic research reported about specific test and analytical methods of the soil thermal conductivities along a pipeline.

1.1 Test Instrument The instrument we use for our study is the field thermal needle system FTN01. This system is a transient thermal conductivity testing method based on the principle of line heat source theory.[3] The key components of the field thermal needle system includes three parts, the non-steady-state probe TP09 ① , mounted at the tip of the lance LN01 ② and the user control and readout from the CRU01 ③. A computer is also needed for downloading and analyzing the data of the measurement.

This paper introduces the testing principle, method and results of soil thermal conductivity for a crude oil pipeline, which crosses tropical desert and grassland of West Africa. Also, based on all the initial testing data, the distribution of the soil thermal conductivity crossing different topographic areas is discussed. 1 TESTING PRINCIPLES AND METHODS Thermal conductivity  is a parameter to describe material's ability to conduct heat. It appeared primarily in Fourier's Law for heat conduction. There are two kinds of methods for measuring thermal conductivity, steady-state method and transient method. Steady-state methods are not suited to field testing, since a well-engineered experimental setup is usually needed. [2] There are many transient methods that can be used for field testing such as transient plane source method, modified transient plane source method, transient line source measurements method and 3ω-method. 3ω -method. [2]

In our test, transient line source measurements method was chosen. This method is carried out by inserting a needle probe into the ground which takes the measurements as the probe heats up. The probe is not required to obtain a constant temperature value because the signal is tracked as a function of time. Although the mathematical analysis of the data is more difficult than steady-state methods, this testing method has the advantage of faster measurement, and it is easier for the needle probes to get to the test depth through a small diameter hole. The steady-state test method can’ can ’t be worked as a location test method. It need long time to obtain a constant temperature value because the signal is tracked as s function of constant temperature. As a laboratory testing method, the process of samples preparation is relatively complex, the moisture content and the compactness of the soil may be quite different from the undisturbed soil. As a result, the transient test method is more suitable than the steady-state test method in pipeline route testing.

Figure 1. Key component of the field thermal needle system

As shown by figure 1, the key component of this field thermal needle system is the non-steady-state probe TP09. A heating wire and a temperature sensor are incorporated in the probe tip. Electricity is loaded to the heating wire, and the soil thermal conductivity is calculated from the observed temperature changes at the sensor. Table 1 shows the specification of the field thermal needle system (FTN01) for soil thermal conductivity measurement. It can be seen from the table that the test range of the soil thermal conductivity is from 0.1 to 6 W/(m ∙℃), and the soil thermal

conductivity under general soil condition is from 0.4 to 3 W/(m∙℃).[4] This suggests that the field thermal needle system (FTN01) is suitable for the soil thermal conductivity measurements along hot oil pipeline route. Table 1. The main parameters of the FTN01 t est system

Measurement method Applicable soils

According to the standards ASTM D 5334-92 and IEEE Std 442-1981. Granular soils, soils, slurries, mud λ range from 0.1 and soft rock in the λ range to 6 (W/m∙ (W/m∙℃).

Duration of the heating cycle Heating Power Temperature range Expected accuracy Repeatability Probe dimensions Power Data storage

Typically Q is adjustable so that temperature rise is not more than 3 ℃. Typically lower than 5 W/m. -30 to +80 °C (TN) 0 to +80 °C (CRU and Cable) Thermal conductivity: ± (6% +0.04 W/m∙℃) for homogeneous soils with good contact to the probe. Thermal Conductivity: ± 2 % 6.35 mm diameter, diameter, length 170 mm 12V/2W maximum 30, the data can be downloaded to PC.

The physical model of this instrument is an infinite line source with constant power per unit length. The temperature profile T(t,r) at a distance r at the time t is as follows. [2,5]

T(t,r) 

Q 4

2

Ei(

r

) 4at

(1)

When an experiment is being performed, the temperature sensor measures the temperature at a fixed distance, and records that temperature in time. The exponential integral can be approximated by making use of the following relation. [2,5] (2) Ei( x)    ln( x)  O( x) This leads to the following expression. [2] 2  Q  r ln( )  ln(t )   4  4at 

(3)

Note that the first term in the bracket on the right-hand side is a constant, while the second term relates to the inverse of time and therefore drops out quite quickly. Thus if the probe temperature is plotted versus the natural logarithm of time, the thermal conductivity can be determined from the slope given knowledge of Q. at

If r

2

Q d ln t 4 dT

(4)

When the test is performed, a constant voltage is loaded on the heating wire. And the heating wire gives out constant heat flow to the soil. At the same time, the probe releases heat to the soil. With the bigger soil thermal conductivity, the probe releases more heat transferred to the soil around the probe, and the probe temperature rises more slowly. To the contrary, the smaller soil thermal conductivity, the quicker rise of the probe temperature. As a result, we can calculate the soil thermal conductivity through recording the changing of the probe temperature with time.

300 seconds (typical)

1.2 Test Principle

T(t, r) 

 

is large enough, Ei equals - γ+ln(t).

The thermal conductivity of line heat source method can be calculated from [2,4,6,7]

1.3 Test methods

Due to the extensive area, the complex terrain, and susceptibility to the natural environment and human operation, the field testing of the soil thermal conductivity is difficult. In order to ensure the accuracy of the testing result, a rigorous testing method is required. By combining the experience of the field testing and referring to the specifications of similar test work, a method for the soil thermal conductivity testing along a hot oil pipeline route was developed. [5,8]

⑴ Determine the test program according to the pipeline route, and develop a detailed test plan, including the locations of the test points, test period and time, etc. The test point locations are generally selected based on the average interval of pipeline mileage. More test points should be increased in special sections such as the seasonal rivers and high divide area in order to improve the representativeness representativeness of the test results. [9] ⑵ Once the field testing begins, confirm the locations of test points identified in the testing plan. Note that the points should represent the soil environment, keep away from nonrepresentative area such as pipeline construction operation areas and the roads, and avoid the impact of the special terrain such as streams, gullies, and man-made structures. [9] Record the location, terrain and the vegetation types and density of the soil at test points. ⑶ Use special drilling tool to drill on the test points to the desired drilling depth in accordance with the maximum depth of burial of the pipeline. Drilling should be kept vertical, and when the drill is down to the desired depth, the loose soil in the bottom of the hole should be removed to ensure that the soil in the test area is undisturbed soil. And then record the soil type, compactness and hardness of the soil in the process of drilling. At the same time, take pictures of the soil. ⑷ At this time, the probe has not been inserted in the soil. Keep the probe in the hole for 2 minutes to equilibrate the temperature of probe with the air in the hole. Then push the probe into the soil at the base of the hole, vertically, and start the test after the soil and probe having exchanged heat for 10 minutes. The test process lasts for about 7 minutes.

⑸ After the test is finished, remember to record test results, replace the soil in the hole, retrieve and examine the equipment, then, continue to test the next point. ⑹ Further treatment of the test results is needed to review the soil thermal conductivity test record of each test point, including recalculating the value of the soil thermal conductivity according to the relationship between the temperature and the time of the test points. And write the report of the soil thermal conductivity testing. 2 TEST RESULTS AND ANALYSIS In this study, the testing area is located at the south-east boundary of the Sahara Desert, and crosses the geomorphologic regions from tropical desert to grassland. The region has its rainy season from June to September, and a dry season from October to May. This study included 6 test cycles, respectively, in February, March, April, May, July and September in 2011.The test points are about 10Km apart and there are 8 test points, on average, between heat stations. The number of test sites may be greater in hilly regions and seasonal riverbed areas. In each cycle, about 43 points were conducted, on average.

Figure 3. Scatter diagram of soil thermal conductivity along the pipeline, part 2

Considering the spacings between adjacent test points, the weighted average soil thermal conductivity for the pipeline route between two adjacent heating stations is calculated by the follow formula N

 ( 

 li 1

li

i

2.1 Test results of thermal conductivity

 ave 

Figure 2 and 3 are scatter diagrams of field testing results. Appendix 1 is a table of the raw data of the field test results.

2

i 1

)

(5)

N

。

l

i

i 1

The calculated average soil thermal conductivity along the pipeline in each month is shown in Table 2. Table 2. The average soil thermal conductivity of each pipeline station interstices

Figure 2. Scatter diagram of soil thermal conductivity along the pipeline, part 1

Station0 — Station0 — Station1 Station1 — Station1 — Station2 Station2 — Station2 — Station3 Station3 — Station3 — Station4 Station4 — Station4 — Station5 Station5 — Station5 — Station6 Average λ

Feb.

Mar.

Apr.

May.

July.

Sept.

W/(m∙℃)

W/(m∙℃)

W/(m∙℃)

W/(m∙℃)

W/(m∙℃)

W/(m∙℃)

0.52

0.54

0.57

0.51

0.53 0.62

0.56

0.58

0.65

0.65

0.62

0.80

0.67

0.48

0.55

0.45

0.91

0.80

0.86

0.75

0.68

0.68

1.11

0.78

0.81

0.81

0.67

0.78

0.97

0.83

0.89

0.88

0.59

0.73

0.90

0.69

0.76

0.67

0.61

0.64

0.83

The test results of six months showed that the thermal conductivity of undisturbed soil along the pipeline route was reduced slowly in the dry season, which was from February to May in our test. And the thermal conductivity is increased significantly in the rain season, which is from May to

September in our test. The main reason is that the soil moisture content at the depth of the buried pipe drops in the dry season, and the thermal conductivity decreases slowly as the result [5]. On the other hand, the soil moisture content goes up in the rain season, and the thermal conductivity goes up too. It is mainly tropical desert from the start of the pipeline to about 200 kilometer, where the soil is mostly yellow dry sandy soil. There are numerous sand dunes from the wind. Testing results in this region are relatively stable, and the thermal conductivity fluctuates slightly between 0.52 and 0.57 W/(m∙℃). At the location about 120 km, the thermal conductivity is significantly higher than the neighboring areas. After significant testing and terrain analysis, we concluded that since this area is located near seasonal rivers. The results are significantly different due to differences in soil moisture content and particle composition. The pipeline route crosses grassland from 200km to 330km.The surface soil are a hard crust of agglomeration sand about 20 centimeters deep on the surface and covered by a thin layer of grass, sparse shrubs, and in some area a few trees. The soil under 20cm deep consists of tiny quartz grain; the hardness is smaller than the surface soil. The soil thermal conductivity of this region sharp fluctuates between 0.6~1.2W/(m ∙℃). From 330km to 463km the pipeline crosses grassland area, where there is also some farmland. Thick grass grows on the surface but has already dried up. There are a variety of plants which are quite dense and a large number of shrubs and relatively tall trees are also common. From the test result, the soil thermal conductivity of this region is mostly in the range of 0.6~0.9 W/(m∙℃). 2.2 The Influence of Moisture Content For the sandy soil under the conditions of the tropical desert and grassland of West Africa, we found that the moisture content is the most obvious effect on the soil thermal conductivity. [10,11] We tested the thermal conductivity of soil under different moisture content conditions, and establish the relation of the measured soil moisture content and the thermal conductivity in this region.

As can be seen in Figure 4, the soil thermal conductivity shows an upward trend with the rising of moisture content. Especially when moisture content is relatively low, soil thermal conductivity is more sensitive to moisture content changes. When moisture content is greater than 10%, soil thermal conductivity is less sensitive to moisture content changes.

Figure 4. The relationship of thermal conductivity and measured soil moisture content

Using linear regression, we developed a relation between the thermal conductivity and moisture content of the soils.

  0.250.4734(0.65  0.58  ln( ln( w  0.5))

(6)

The formula applies to the powdery sand of the test region. [3] The soil moisture content along the pipeline can be estimated according to the measured soil thermal conductivity using this relationship. 2.3 The influence to the pipeli ne operation The aim of testing the soil thermal conductivity along the pipeline route is for calculating the heat dissipation of the pipeline, and helps select an economical and safe operation scheme. Take the Niger crude oil pipeline for example; the effects of the soil thermal conductivity on the total heat transfer coefficient, the oil temperature and the fuel consumption of the pipeline are discussed.

The station spacing of the Niger pipeline is approximate 80Km. The pipeline has an external diameter of 323mm and a burial depth of 1.3m. The crude transported in the pipeline has a condensation point of 37 ℃. The lowest allowed in-station oil temperature is 40 ℃. Supposing the calculation period is in September, September, when the temperature around the burial depth of the pipeline is 33 ℃ and the average soil thermal conductivity along the pipeline ranges from 0.45 to 1.11W/(m ∙ ℃ ). The effects of the soil thermal conductivity on the pipeline operation condition are stimulated in the research on condition that others relevant parameters remain unchanged. The results are shown in table 3.

Table 3.

Soil Thermal Conductivity

The influence of soil thermal conductivity to pipeline operation

Overall Heat Out-Station In-Station Transfer Temp. Temp. Coefficient 2

Temp. Fuel Rise Consumption

W/(m ∙℃)

W/(m ∙℃)

℃

℃

℃

kg/h

0.45

1.00

44.7

40.0

4.7

78.28

0.55

1.23

46.7

40.0

6.7

111.59

0.65

1.45

49.0

40.0

9.0

149.90

0.75

1.67

51.6

40.0

11.6

193.21

0.85

1.90

54.7

40.0

14.7

244.84

0.95

2.12

58.3

40.0

18.3

304.80

1.00

2.23

60.4

40.0

20.4

339.78

1.10

2.45

64.9

40.0

24.9

414.73

As table 3 shows, the soil thermal conductivity, the out-station oil temperature and the fuel consumption all rise significant with the increment of the soil thermal conductivity. While the rise of the out-station oil temperature threatens the safety of the pipeline, the rise of the fuel consumption affects economic performances of the pipeline directly. Consequently, the accuracy of the soil thermal conductivity tested along the pipeline makes good sense in selecting an optimized operation scheme.

3 CONCLUSIONS 1) During the dry season, the average soil thermal conductivity is 0.4~0.8W/(m∙℃). And during the rainy season, the average soil thermal conductivity is 0.5~1.1 W/(m∙℃). 2) The rainfall of the test area shows obvious seasonal characteristics, so the soil thermal conductivity also shows a significant seasonal variation. In the dry season, which is from February to May in our test, the soil thermal conductivity decreases from 0.69 to 0.61 from February to May, with the evaporation of water. And the soil thermal conductivity in the rainy season increases significantly from 0.61 to 0.83 with the increasing of moisture content from May to September. 3) The testing process proves that the soil thermal conductivity is more sensitive to the influence of moisture content. Especially when moisture content is lower, the smaller fluctuations of moisture content will have a greater impact on thermal conductivity. 4) Soil thermal conductivity is influenced by the terrain, so the soil thermal conductivity along the pipeline shows complicated and changeable characteristics. The thermal conductivity of typical tropical desert soil is generally lower than other areas, and the difference of the soil thermal conductivity in rainy and dry season is not as obvious as other areas. The thermal conductivity of typical grassland soil is generally greater than

desert area, and the difference of the soil thermal conductivity in rainy and dry season is more significant. 5) The paper provides a calculation method for the weighted average soil thermal conductivity for the pipeline route between two adjacent heating stations.

ACKNOWLEDGMENTS The authors gratefully acknowledge the financial support from China Oil and Gas Exploration and Development Company (CNODC) and China National Petroleum Company (CNPC Niger Petroleum S.A.)

REFERENCES [1] Yang Xiaoheng, Pipeline Design and Management : Petroleum University Press, May 2006, pp.76-79 [2] Wikipedia, Wikipedia, Thermal Thermal conductivity measurement, measurement, Received Feb. 12. 2012, from http://en.wikipedia.org/wiki/Therma http://en.wikipedia.org/wiki/Thermal_ l_ conductivity_measurement [3] Xiao Lin, Li Xiaozhao, Xiaozhao, Moisture Content and and Porosity of The Soil Thermal Conductivity of Laboratory Experiments: Journal of PLA University of Science and Technology (Natural Science) .2008 June 9 Phase III. pp. 241-247 [4] J. Lipiec, B. Usowicz, A. Ferrero, Impact of soil compaction and wetness on thermal propertiesof sloping vineyard soil, International Journal of Heat and Mass 3847 Transfer 50 (2007) 3837 – 3847 [5] Hubert Lebo, Kuo K. Wang, Wang, Line-Heat-Source Line-Heat-Source Thermal Thermal Conductivity Measuring System, United States Patent , Patent Number: 4,861,167 [6] Carslaw, Carslaw, H. S. and Jaeger, J. C., Conduction Conduction of Heat in Soils, Oxford Press, 2nd ed., 1964, pp. 58-60, 344-345 [7] Krishpersad Krishper sad Manohar, David W.Yarbrough, W.Yarbrough, James R. Booth, Measurement of Apparent Thermal Conductivity by the Thermal Probe Method, American Society for Testing and Materials,100 Barr Harbor Drive, West Conshohocken, pp.19428-2959 [8] IEEE Std 442-1981, IEEE Guide for Soil Thermal Resistivity Measurements, IEEE Standards Board, Reaffirmed Reaffirmed 1996. [9] Hou Fangzhuo, Material Thermal Conductivity Measurement with a Probe Method: Petroleum University (Natural Science), 1994 18 volumes. pp. 94-99 [10] Arnepalli Dali Naidu, 1A generalized procedure for determining thermal resistivity of soils, International Journal of Thermal Sciences, 43 (2004) 43 -51. [11] Bryan R. Becker, Anil Misra, Brian A. Fricke, Development of Correlations for Soil Thermal Conductivity: Int. Comm. Heat Mass Transfer, Vol.19, pp.56-68, 1992

ANNEX A INITIAL DATA DATA OF THE SOIL THERMAL THERM AL CONDUCTIVITY MEASURMENT Feb. Mar. Apr. May. July. Sept. soil thermal soil thermal soil thermal soil thermal soil thermal soil thermal mileage mileage mileage mileage mileage mileage conductivity conductivity conductivity conductivity conductivity conductivity km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

1 1 15 15 30 30 41 41 55 55 65 65 75 75 81 81 100 100 110 110 120 120 129.5 129.5 139.5 139.5 149.5 149.5 159.5 179 179 189 189 199 199 209 209 219 219

0.57 0.54 0.57 0.73 0.41 0.52 0.41 0.42 0.5 0.48 0.58 0.45 0.56 0.67 0.54 0.55 0.41 0.45 0.67 0.78 0.97 1.21 0.61 0.48 0.46 0.47 0.61 0.47 0.69 0.53 0.51 0.43 0.46 0.48 0.52 0.56 0.59 0.58 0.51

98 103 110 113 116 119 129.5 139.5 144.5 149.5 154.5 158.5 164 174 184 194 199 204 204 214 224 234 241.5 251.5 251.5 261.5 271.5 281.5 291.5 301.5 311.5 316.7 327.5 337.5 347.5 357.5 367.5 377.5 387.5

0.5 0.49 0.68 0.47 1.12 0.48 0.43 0.44 0.51 0.73 0.43 0.47 0.55 0.46 0.43 0.45 0.54 0.76 1.2 0.67 0.74 0.86 1.06 0.57 1.16 0.68 0.78 1.02 0.72 1.09 0.69 0.68 0.92 0.76 0.7 0.84 0.85 0.62 0.98

39 49 59 69 79 89 99 104.5 109 119 129 132.5 137.5 139 149 156 162.5 172.5 182.5 192.5 203 221 230.5 235.5 241.5 251.5 261.5 278.5 288.5 298.5 308.5 319.5 327 336.5 346.5 354.5 364.5 374.5 384.5

0.52 0.42 0.53 0.46 0.67 0.53 0.45 0.55 0.48 1.16 0.53 0.5 0.47 0.48 0.77 0.51 0.49 0.52 0.4 0.47 0.41 0.48 0.54 0.54 0.41 1.13 0.8 0.57 0.53 0.68 1.12 0.86 0.88 0.75 0.7 0.75 0.71 0.78 1.01

8 18 28 38 48 58 68 78 86.5 96.5 106.5 116.5 126.5 136.5 146.5 156.5 175.5 185.5 195.5 205.5 215.5 225.5 235.5 243.5 253.5 263.5 273.5 283.5 293.5 303.5 313.5 319.5 329.5 339.5 349.5 359.5 369.5 379.5 399.5

0.67 0.52 0.51 0.55 0.46 1.31 0.69 0.48 0.57 0.64 0.55 0.53 0.49 0.57 0.47 0.55 0.52 0.6 0.48 0.74 0.51 0.56 0.59 0.49 0.46 0.47 0.49 1.14 0.99 0.78 0.73 0.7 0.46 0.73 0.46 0.77 0.64 0.86 0.48

1 11 21 31 41 51 61 71 81 89.5 99.5 109.5 119.5 129.5 139.5 149.5 159.5 168.5 178.5 188.5 198.5 208.5 218.5 228.5 238.5 246.5 256.5 266.5 276.5 286.5 296.5 306.5 316.5 322.5 332.5 342.5 352.5 362.5 372.5

0.46 0.51 0.46 0.66 0.48 0.46 0.84 0.42 0.86 0.62 0.77 0.47 1.29 0.58 0.57 0.48 0.39 0.39 0.44 0.37 0.47 0.55 0.48 0.5 0.37 0.51 0.88 0.56 0.47 0.58 1.17 0.71 0.54 1.12 0.79 0.67 0.51 1.19 0.86

1 11 21 31 41 51 61 71 81 89.5 99.5 109.5 119.5 129.5 139.5 149.5 159.5 168.5 178.5 188.5 198.5 208.5 218.5 228.5 238.5 246.5 256.5 266.5 276.5 286.5 296.5 306.5 316.5 322.5 332.5 342.5 352.5 362.5 372.5

0.46 0.51 0.46 0.66 0.48 0.46 0.84 0.42 0.86 0.62 0.77 0.47 1.29 0.58 0.57 0.48 0.39 0.39 0.44 0.37 0.47 0.55 0.48 0.5 0.37 0.51 0.88 0.56 0.47 0.58 1.17 0.71 0.54 1.12 0.79 0.67 0.51 1.19 0.86

continued Feb. Mar. Apr. May. July. Sept. soil thermal soil thermal soil thermal soil thermal soil thermal soil thermal mileage mileage mileage mileage mileage mileage conductivity conductivity conductivity conductivity conductivity conductivity km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

km

W/(m∙℃)

229 229 239 239 248 248 258 258 268 268 277.5 277.5 288 288 298 298 308 308

1.04 0.67 0.81 0.63 0.75 0.86 0.47 0.78 0.63 0.82 0.73 0.55 1.1 0.99 0.84 0.96 1.12 1.04

391.5 401.5 411.5 421.5 431.5 441.5 451.5 461.5

0.97 0.84 0.79 0.83 0.96 0.91 0.85 1.04

399.5 409.5 419.5 429.5 439.5 449.5 459.5

1.04 0.97 0.83 0.73 0.79 0.8 1.02

409.5 419.5 429.5 439.5 449.5 459.5

0.37 0.37 0.75 0.89 0.71 0.59

382.5 392.5 396.5 411.5 417.5 421.5 431.5 441.5 451.5 461.5

0.36 0.76 0.45 0.86 0.49 1.16 0.84 0.86 0.54 0.66

382.5 392.5 396.5 411.5 417.5 421.5 431.5 441.5 451.5 461.5

0.36 0.76 0.45 0.86 0.49 1.16 0.84 0.86 0.54 0.66

316.6 316.6 330 330 345 345 354.5 354.5 362 362 372 372 383 383 392.7 392.7 402 402 414 414 421 421 428.4 428.4

0.6 0.66 0.77 0.83 0.73 0.77 0.8 0.84 0.62 0.76 0.94 0.92 0.81 0.81 0.85 0.71 0.94 0.98 0.45 0.47 0.96 0.82 0.36 0.38

continued Feb. Mar. Apr. May. July. Sept. soil thermal soil thermal soil thermal soil thermal soil thermal soil thermal mileage mileage mileage mileage mileage mileage conductivity conductivity conductivity conductivity conductivity conductivity km

W/(m∙℃)

440 440 455 455 457.5 457.5 459.5 459.5 460 460 460.5 460.5 461.5 461.5

0.75 0.88 0.89 1.15 1.14 1.09 0.84 0.82 0.95 1.07 0.86 0.89 0.78 0.9

km

W/(m∙℃)

km

W/(m∙℃)

W/(m∙℃)

km

W/(m∙℃)

km

km

W/(m∙℃)

ANNEX B INITIAL DATA DATA OF THE THERMAL CONDUCTIVITY AND THE MEASURED SOIL SOI L MOISTURE CONTENT CONT ENT soil water content

soil thermal conductivity

soil water content


soil water content


V/V

W/(m∙℃)

V/V

W/(m∙℃)

V/V

W/(m∙℃)

0.5

0.3

5.83

0.76

12.7

1.28

0.83

0.37

6.66

0.91

12.9

1.18

3

0.74

6.66

1.03

13

1.08

4

0.78

8.6

1. 18 1.18

13.1

1.13

3.5

0.74

10.5

1.08

13.2

1.03

4.5

0.8

10.6

1.02

13.6

1.15

1.66

0.46

10.7

1.28

13.7

1.08

2

0.76

10.7

1.12

13.7

1.15

2.52

0.47

10.8

1.06

13.8

1.24

3.35

0.75

11.2

1

13.9

1.05

3.7

1

11.3

1.11

14

1.33

4.18

0.86

11.6

0.98

14

1.21

IPC2012-90291

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