* ⋕ᯕᜅ✙ Õᖅ ၰ ⪹ĞŖ⦺ŝ ၶᔍŝᱶ ([email protected])
*** ⋕ᯕᜅ✙ Õᖅ ၰ ⪹ĞŖ⦺ŝ ᕾᔍŝᱶ ([email protected])
Received March 5, 2013/ revised June 27, 2013/ accepted September 4, 2013
Copyright ⵑ 2013 by the Korean Society of Civil Engineers
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0)
ǣǣȀȀǤǤȀͳͲǤͳʹͷʹȀ ǤʹͲͳ͵Ǥ͵͵ǤǤʹ͵ͺͳ
Ǥ ǤǤ
⺺≾#⽾⇖ⴖ#⮲ⷂᦂᦂἺ#ኞᷢ㬚#PHC ⮎ᛆ⽾㣊ⴺⴖ#⮲#ሮᦗ#⇍#
㣊ⴺ#ᇂ#⮲#ᇂ⛫#㯂♿⮎#ᢾ㬚#⟖㐖㬲⛛#⮮ጪ
ճָ෮ ȵଗজ ȵࢮܑ ȵଲ
Go, Gyu Hyun*, Yoon, Seok**, Park, Do Won***, Lee, Seung-Rae****
Thermal Behavior of Energy Pile Considering Ground Thermal Conductivity and Thermal Interference Between Piles
ABSTRACT
In general, ground’s thermal properties, types of heat exchanger, operational method, thermal interference between piles can be considered as key factors which affect the thermal performance of energy pile. This study focused on the effect of these factors on the performance by a numerical model reflecting a real ground condition. Depending on the degree of saturation of ground, pile’s heat transfer rate showed a maximum difference of three times, and the thermal resistance of pile made a maximum difference of 8.7%. As for the type of heat exchanger effects on thermal performance, thermal efficiency of 3U type energy pile had a higher value than those of W and U types. The periodic operation (8 hours operation, 16 hours pause) can preserve about 20% of heat efficiency compared to continuous operation, and hence it has an advantage of preventing the thermal accumulation phenomenon. Thermal interference effect in group piles may vary depending on the ground condition because the extent decreases as the ground condition varies from saturated to dry. The optimal separation distance that maintains the decreasing rate of heat efficiency less than 1% was suggested as 3.2D in U type, 3.6D in W type, and 3.7D in 3U type in a general ground condition.
Key words : Energy pile, Thermal performance analysis, Saturation, Thermal interference, Operating evaluation
Ⅹಾ
ᯝၹᱢᮝಽᨱթḡ❭ᯝ᮹ᩕᱢᖒ܆ᨱᩢ⨆ᮥᵝ۵ᵲ⦽ᯙᯱಽḡၹ᮹ᩕྜྷᖒ, ᩕƱ⪹ʑ⩶┽, ᬕᬊႊჶ, ❭ᯝeᩕeᖎ॒ᯕŁಅࢁᙹᯩ
݅. ᅙᩑǍᨱᕽ۵ḡၹ᮹ᝅᱽ᳑Õᮥၹᩢ⦽ᙹ⊹༉ߙᮥ☖⧕ᯕॅᯙᯱॅᯕၙ⊹۵ᩢ⨆ᮥᔕ⠕ᅕᦹ݅. ḡၹ᮹⡍⪵ᱶࠥᨱᕽ❭ᯝ᮹ᩕ
Ʊ⪹ᮉᮡ↽ݡ3႑ʭḡ₉ᯕෝᅕᩡᮝ໑, ᩕᱡ⧎ᮡ↽ݡ8.7%᮹₉ᯕaၽᔾ⦹ᩡ݅. ੱ⦽ᩕƱ⪹ʑᮁ⩶ᯕ❭ᯝ᮹ᩕᖒ܆ᨱᩢ⨆ᮥᵝ໑, 3U-TypeᯕWӹU-Typeᨱእ⧕ᔢݡᱢᮝಽ׳ᮡᩕ⬉ᮉᮥᅕᩡ݅. ᬕᬊႊჶᨱᯩᨕᕽ, ᇡᇥa࠺(8ea࠺, 16e⮕ḡ) ᩑᗮa࠺ᨱእ
⧕ᕽ᧞20%᮹ᩕ⬉ᮉᮥᅕᱥ⧁ᙹᯩᮝ໑, ᰆʑᱢᯙᩕ⇶ᱢ⩥ᔢᮥႊḡ⦹۵ߑᮁญ⦹݅. ḡၹ᮹᳑ÕᨱǑั૾ᨱ᮹⦽ᩕeᖎᱶࠥa
ݍḡ۵ߑ, ḡၹᯕ⡍⪵ᔢ┽ᨱᕽÕ᳑ᔢ┽ಽiᙹಾǑั૾ᨱ᮹⦽ᩕeᖎ⬉ŝ۵qᗭ⦽݅. ᯝၹᱢᯙḡၹ᳑ÕᨱᕽᩕƱ⪹qᗭᮉ1%ၙอ
ᮥᮁḡ⦹۵ᱢᱶᯕĊÑญ۵U-Typeᨱᕽ↽ݡ3.2D, W-Typeᨱᕽ↽ݡ3.6D, 3U-Typeᨱᕽ↽ݡ3.7Dಽᔑᱶࡹᨩ݅.
áᔪᨕ ᨱթḡ❭ᯝ, ᩕᖒ܆⧕ᕾ, ⡍⪵ࠥ, ᩕeᖎ, ᬕᬊ⠪a
ݓъėॡ
1. ᕽು
ḡᩕᨱթḡ۵ᩑᵲᯝᱶ⦹íᮁḡࡹ۵ḡᵲ᮹᪉ࠥෝ⪽ᬊ⦹۵
⊽⪹Ğᨱթḡᬱᮝಽᕽ↽ɝᨱ⪵ࢱaࡹŁᯩ۵ᝁᰍᔾᨱթḡ
ᱶ₦ᨱᇡ⧊⦹໑, ┽᧲ᨱթḡ, ⣮ಆᨱթḡ᪡ᇩᨕݡℕᨱթḡ ಽᕽฯᮡbŲᮥၼŁᯩ݅. ✚⯩ḡᵲᩕƱ⪹ʑᜅ▽ᮡᯕᔑ⪵┥
ᗭၽᔾᱡqၰᨱթḡᱩ᧞⩶ʑᚁᯥŝ࠺ᨱᰆᗭᨱǍᧁၼḡ
ᦫŁ ᱢᬊ⧁ ᙹ ᯩ۵ ᮁእ░ᜅ(ubiquitous)ʑᚁᯕ݅(Yoon et al., 2011). ḡᵲᩕƱ⪹ᰆ⊹۵}ႊ⩶ŝၡ⠱⩶ᯕᯩᮝ໑, ၡ⠱⩶ᮡ
݅ᙹ⠪⩶ŝᙹḢ⩶ᮝಽǍᇥᯕࡽ݅. ᙹ⠪⩶ᩕƱ⪹ʑ۵ࠥ
ŞᯕӹⅭḡᩎŝzᯕմᮡᇡḡᨱᕽᱢᬊᖒᯕᳬᮡၹ໕, দᯕ
᳢ŁၡḲḡᩎᯕฯᮡᬑญӹ᮹Ğᬑ, ᙹḢၡ⠱⩶Ǎ᳑aᅕ݅
ᯝၹᱢᯕ݅. ᙹḢၡ⠱⩶ᮡǕ₊⬥ᩕƱ⪹ʑෝๅᖅ⦹Łə
ᵝ᭥ಽ əᬑ✙ ₥ᬡ(grouting)ᮥ ⧉ᮝಽ៉ ᵝ᭥ ☁᧲ŝ᮹ ᩕ
ᱲⅪᮥᬊᯕ⦹í⦹Ł☁᧲᪅ᩝᮥႊḡ┉݅. Ǖ₊Ŗ᮹ḢĞᮡ
ᅕ☖10~15cmಽᕽᅕᨕ⪡᮹ḢĞᯕ᯲ʑভྙᨱᙹḢၡ⠱⩶ᨱᕽ ۵ U-type᮹ ḡᵲᩕƱ⪹ʑa ձญ ᔍᬊࡽ݅.
⦹ḡอŖᗭࡹ۵እⅩʑŖእྙᱽಽᯙ⦹ᩍ↽ɝᨱ ۵ᨱթḡ❭ᯝಽᇩญ۵ᔩಽᬕ⩶┽᮹ḡᵲᩕƱ⪹ʑaᱢᬊࡹŁ
ᯩ݅. ᯕ۵Ǎ᳑ྜྷ᮹ั૾ᨱḡᵲᩕƱ⪹ʑෝๅ᯦⦽⩶┽ಽ៉Ⅹʑ
Ŗእ ྙᱽෝ ⧕đ⧁ ᙹ ᯩᮝ໑, Ǎ᳑ᱢᮝಽࠥ ᦩᱶᖒᮥ ≉⧁
ᙹᯩ۵ᰆᱱᯕᯩ݅(Ministry of Science and Technology, 2006).
ᨱթḡ❭ᯝᮡᙹḢၡ⠱⩶ᨱእ⧕ᅕᨕ⪡᮹ḢĞᯕⓍŁʙᯕ۵
Ṉʑভྙᨱᩕ⬉ᮉ᷾ݡෝ᭥⦽݅᧲⦽ᩕƱ⪹ʑaᔍᬊࡹ໑, U-type ᯕᨱW-type ၰ3U-type ॒᮹ᩕƱ⪹ʑaᔍᬊࡽ݅.
ᨱթḡ❭ᯝ᮹ᩕᱢÑ࠺ᨱ ᩢ⨆ᮥᵝ۵ aᰆ ᵲ⦽ᯙᯱ۵
❭ᯝԕᇡ᮹ᩕᱡ⧎ŝ❭ᯝᮥࢹ్Łᯩ۵ḡၹ᮹ᩕྜྷᖒᯕ݅.
ᨱթḡ❭ᯝ᮹ᩕ⬉ᮉᮥ᷾a┅ʑ᭥⦽ʑ᳕ᩑǍॅᯕฯᯕᙹ⧪
ࡹŁ ᯩḡอ(Song, 2011; Bourne-Webb et al., 2009; Sohn and Choi, 2012) ݡᇡᇥʑĥᱢšᱱ⪚ᮡั૾ԕᇡᱢšᱱᨱᕽ᮹
ᖒ܆}ᖁᨱⅩᱱᮥ฿⇵Łᯩᮥᐱ, ḡၹ᮹᳑ÕᮥŁಅ⦽ᨱթḡ
❭ᯝᨱ ݡ⦽ ᩑǍ۵ ၙၙ⦽ ᝅᱶᯕ݅. ᅙ ᩑǍ۵ ḡၹ Ŗ⦺ᱢ
šᱱᨱᕽ ḡၹ᮹ ᳑Õ ᄡ⪵a ᨱթḡ❭ᯝ᮹ ᩕ Ñ࠺ᨱ ၙ⊹۵
ᩢ⨆ᨱݡ⧕ᕽᇥᕾ⧕ᅕŁ, ḡၹ᮹ᩕᱥࠥࠥᄡ⪵ෝŁಅ⦽ᖅĥ
ʑᵡᮥ ᅕ᪥⦹Łᯱ ⦹۵ߑ ə ᮹ၙa ᯩ݅. ੱ⦽ Ǒ ั૾ᨱᕽ
ᰆʑᱢÑ࠺ᨱၽᔾ⦹íࡹ۵❭ᯝeᩕeᖎ⩥ᔢᨱݡ⧕ᕽ
Ǎ⧕ᅕŁ, ᩕ eᖎᮥ ↽ᗭ⪵ ⧁ ᙹ ᯩ۵ ❭ᯝ e ↽ᗭ ᯕĊ
Ñญෝ ᱽ⦹ᩡ݅. əญŁ ḡၹ᮹ ᳑Õᄡ⪵, ᩕ Ʊ⪹ʑ ᮁ⩶, ᬕᬊ ႊჶ(ᩑᗮ ੱ۵ ᇡᇥa࠺), Ǒ ั૾ᨱ ᮹⦽ eᖎ ⬉ŝෝ
ᵝᩢ⨆ᯙᯱಽᖅᱶ⦹ᩍᯕॅᯙᯱᨱݡ⦽ᨱթḡ❭ᯝ᮹݉ʑᱢ
ᩕᱢ ᖒ܆ᮥ እƱ ᇥᕾ⦹ᩡ݅.
2. ᨱթḡ❭ᯝ᮹Ñ࠺⧕ᕾᮥ᭥⦽ᙹ⊹༉ߙ
ᅙᩑǍᨱᕽ۵ᮁ⦽ᗭ⥥ಽəఉᯙCOMSOL Multiphysics 4.3a (Comsol multiphysics, 2012)ෝᯕᬊ⦹ᩍᨱթḡ❭ᯝ᮹ᖒ܆
ၰ ᩕ Ñ࠺ ⧕ᕾᮥ ᭥⦽ ᙹ⊹⧕ᕾ༉ߙᮥ อॅᨩ݅. COMSOL Multiphysics۵Computational Fluid Dynamic (CFD) ⧕ᕾᮥ
☖⧕ ❭ᯕ⥥ ᯙᨱᕽ᮹ ᮁℕ᮹ ⮱ᮥ ༉ᔍ⦹໑, ❭ᯕ⥥ ᵝᄡ
ๅḩŝ᮹ ᩕ Ʊ⪹ᮥ ᩑĥ⦹ᩍ ⧕ᕾᮥ ⧁ ᙹ ᯩ݅. ᅙ ᩑǍᨱᕽ
}ၽࡽᙹ⊹⧕ᕾ༉ߙ᮹ḡ႑ႊᱶᮡᩕƱ⪹ʑ ԕᇡᙽ⪹ᙹᨱ
᮹⦽ݡඹၰᱥࠥ᪡əᬑ✙ၰPHC ั૾, ḡၹๅḩᨱ᮹⦽
ᩕ ᱥࠥෝ ⡍⧉⦹Ł ᯩ݅.
2.1 ࢱছଭવୢۜ
ḡၹᨱᕽ᮹ᩕᱥݍᮡⓍíᱥࠥ(conduction), ᅖᔍ(radiation), əญŁݡඹ(convection)᮹⩶┽ಽᯕᨕḥ݅. ᯕᵲᩕᱥࠥ۵
ྜྷḩԕ ᯙᱲ⦹۵ ᇥᯱॅᔍᯕ᮹ ᪉ࠥĞᔍᨱ ᮹⧕ၽᔾ⦹۵ ᩕ
ᯕ࠺ ີ⍅ܩ᷹ᯕ໑, ⧎ᔢ ᪉ࠥa ׳ᮡ ᩢᩎᨱᕽ ԏᮡ ᩢᩎᮝಽ
ᯕ࠺⦹ࡹ, ࢱ ᩢᩎ᮹ ᪉ࠥa ⠪⩶ᔢ┽ᨱ ࠥݍ⧁ ভʭḡ ḥ⧪ᯕ
ࡽ݅. ᩕᱥࠥࠥ۵ࢱ̹a1mᯙ⠪❱ᨱ1Kelvin᮹ᩕᯕa⧕Ჭᮥ
ভᱥݍࡹ۵ᩕ᮹᧲ᮥWattಽ⊂ᱶ⦹ᩍӹ┡ԕŁ݉᭥۵W/mKಽ
⢽⩥ࢁ ᙹ ᯩ݅.
⦽⠙, ḡ⦹ᙹ᮹⮱ᯕᨧÑӹ⚍ᙹĥᙹaๅᬑԏᮡḡၹ᮹
Ğᬑ, ݡඹੱ۵ᯕඹ᮹ᩢ⨆ᮡၙၙ⦽äᮝಽŁಅ⧁ᙹᯩ݅(Rees et al., 2000). ᕽ ᅙ ᩑǍᨱᕽ۵ ḡၹ᮹ ᩕ ᱥݍᮡ ᱥࠥ᮹
⩶┽ಽᮁၽࡽ݅ŁŁಅ⦹ᩡᮝ໑ᯕ۵Eq. (1)᮹ᱥࠥႊᱶᮝಽ
⢽⩥ࢁ ᙹ ᯩ݅(Incropera and Dewitt, 2002; Lurie, 2008).
Ň
Ǝć Şƒ Ş
ƃƖƒ
ᩍʑᕽ, Ň ۵ ၡࠥ,
Ǝ۵ እᩕ,
ƃƖƒ۵ ❭ᯕ⥥ ᇡ᮹ ᪉ࠥ, Ł ۵ๅḩ᮹ᩕᱥࠥࠥ, ª ۵ๅḩԕᇡಽᇡ░᮹ᩕၽᔾᮥ᮹ၙ⦽݅.
2.2 વ֗ฅ׆০ฅଭવୢۜ
ݡඹၰᱥࠥᨱ᮹⦽ᙹ⊹༉ߙ᮹ḡ႑ႊᱶᮡEq. (2)᪡z݅.
(2)
ᩍʑᕽ Ň
Ƅ۵ᙽ⪹ᙹ᮹ၡࠥ,
Ǝ۵❭ᯕ⥥᮹݉໕ᱢ, ª
ƕſƊƊᮡ
❭ᯕ⥥ ᄞ໕ᨱᕽ᮹ ᩕ Ʊ⪹ᨱ ᮹⧕ ၽᔾ⦹۵ ᩕᬱᮥ ӹ┡ԕ໑,
Fig. 1. Ground Conditions Used in the Simulations
Table 1. Input Thermal Properties of Materials Used in the Simulations
Material Thermal conductivity(W/m·K)
Specific heat capacity(J/kg·K)
Density (kg/m3)
Soil1 1.10 1160 1800
Soil2 2.40 1280 2140
Rock 3.24 823 2640
Equivalent ground 2.11 1166 2111
Grout 2.02 840 3640
PHC 1.62 790 2700
*Polybutylene
pipe 0.38 525 955
Circulating water 0.57 4200 1000
*Given by manufacturer
ᯕ۵ Eq. (3)ᨱ ӹ┡ԙ ၵ᪡ zᯕ Eq. (1)᮹ ❭ᯕ⥥ ᇡᨱᕽ
ᯝᨕӹ۵ᩕᱥݍŝᵲℊࡽ݅. Fig. 3ᮡ❭ᯕ⥥ᄞ໕ᨱᕽᙽ⪹ᙹ
⮱ŝ❭ᯕ⥥ᇡๅḩᔍᯕᨱᕽᩕᱥݍᯕᕽಽᩑĥࡹ۵ŝᱶᮥ
ᅕᩍᵡ݅. ੱ⦽, Ƅ
ć ÏƂ Ň çƓç
Ɔ Ð⧎ᮡᱱᖒᨱ᮹⦽ᩕᗱᝅᮥ᮹ၙ⦹໑, Ƃ
Ɔ۵⠪Ɂᙹญ⦺ᱢḡᮝಽᕽ Ƃ
Ɔá Ñ
Ǝ³ ( ³ ۵ᮅᄡʙᯕ)ಽ⢽⩥
⧁ᙹᯩ݅. ੱ⦽ Ƅ
۵Darcy᮹ྕ₉ᬱษₑĥᙹ, Ɠ ۵ᱲᖁᗮࠥ, Ł
Ƅ۵ ᙽ⪹ᙹ᮹ ᩕᱥࠥࠥෝ ӹ┡ԙ݅.
ª
ƕſƊƊá Ɔ³Þ
ƃƖƒà
Ƅß Þ°îƋß (3)
ᩍʑᕽ
ƃƖƒ۵ ❭ᯕ⥥ ᇡ ᩢᩎᨱᕽ᮹ ᪉ࠥ,
Ƅ۵ ᙽ⪹ᙹ
᭥: m)᮹Œᮝಽ⢽⩥ࡹ໑, ❭ᯕ⥥݉໕ᯕᬱ⩶ᯝĞᬑ, ᮁ⬉ Ɔ³ ۵
Eq. (4)᪡ zᯕ ӹ┡ԝ ᙹ ᯩ݅.
ÞƆ³ß
ƃƄƄá ć
ć Ɛ
×Ɔ Î â
Ƈ ƌƒć Ɛ
§Ɔ Î â
ƃƖƒ ƌ á Îā
§Ė
Ę
ć Ł
ƌ ć Ɛ
ƌ àÎƐ
ƌę
ě
Ïņ (4)
ᩍʑᕽ Ł
ƌŝ Ɛ
ƌᮡbb ƌ ჩṙᄞ໕᮹ᩕᱥࠥࠥ᪡ၵˆၹĞᮥ
ӹ┡ԕŁ, Ɔ
Ƈ ƌƒ᪡ Ɔ
ƃƖƒ۵❭ᯕ⥥ᦩŝၵˆ᮹⦥ᩕᱥݍ
ĥᙹෝ ӹ┡ԙ݅.
2.3 ౿ࡦ܄ୡܤ׆࣭વࢄনࢫැজՍ ǎԕḡၹ᮹ḡၹŖ⦺ᱢ✚ᖒᮥᙹ⊹༉ߙᨱษӹᱶ⪶⯩ၹᩢ
┅۵aᨱ ə ༉ߙ᮹ ᝁᖒŝ ⧊ญᖒᯕ ᅕᰆࡽ݅. ᯕෝ
᭥⧕ᅙᩑǍ۵ᙹᬱ⪙ๅᝅᄡᱥᗭŖᔍᨱᯕᬊࡽḡၹ᳑ᔍᅕŁᕽ
ෝₙ᳑⦹ᩍḡၹྜྷᖒᮥ༉ߙᨱᱢᬊ⦹ᩡ݅. ั૾ᵝᄡ᮹ḡၹᮡ
ḡ⦹ᙹ᭥ෝʑᵡᮝಽᇩ⡍⪵⊖ŝ⡍⪵⊖ᮝಽӹڹᨕᲙᯩᮝ໑ั
૾᮹⦹ၹᇡ۵ᦵၹ⊖ᮝಽǍᖒࡹᨕᯩ݅(Fig. 1). ᇩ⡍⪵⊖ŝ⡍⪵
⊖᮹ᩕᱥࠥࠥ۵Ʊഭෝ₥≉⦽⬥⩥ᰆ݉᭥ᵲపŝ⧉ᙹእಽ
݅ḥ⬥┱⋉⨹ᮥᙹ⧪⦹ᩍ⊂ᱶ⦹ᩡᮝ໑, ᦵၹ⊖᮹ᩕᱥࠥࠥ۵
šಉྙ⨭(Geothermal design studio, 2012)ᮥₙ᳑⦹ᩡ݅. ⧕ᕾ᮹
e⠙⪵ෝ᭥⧕ᕽ݅⊖ᮝಽᯕᨕḥḡၹᮥ॒aḡၹᮝಽ⪹ᔑ⦽
⬥ᩕྜྷᖒᨱݡ⦽⧕ᕾᮥᙹ⧪⦹ᩡ݅. ॒aᩕᱥࠥࠥෝᔑᱶ⦹ʑ
᭥⧕ᕽEq. (5)᪡zᮡ॒aᩕᱥࠥࠥ⪹ᔑᮥᯕᬊ⦹ᩡ݅. ḡᩕᖅ ĥ⥥ಽəఉᨱᕽ aᰆ ձญ ᔍᬊࡹ۵ GLD 2012 ⥥ಽəఉᮡ
Drilling Log Conductivity Calculator۵ᔩಽᬕ༉ऩᮥ☖⧕
݅⊖ḡၹ᮹ᩕᱥࠥࠥෝŁಅ⦹Łᯩ۵ߑEq. (5)᪡zᮡ॒aᩕᱥ
ࠥࠥ ⪹ᔑᮥ ᯕᬊ⦹ᩡ݅. ᯕ۵ እ࠺đ☁᮹ ᩕ ᱥݍᮡ ᱥࠥᨱ
᮹⦽ᩕᱥݍᯕḡ႑ᱢᯕ໑(Rees et al., 2000), ⡍⪵☁ᨱᕽḡ⦹ᙹ
⮱ᮥŁಅ⦹ḡᦫᮥĞᬑ, ᱥࠥ᮹ႊ⨆ᮡ॒ႊᖒᯕŁᮁ⇵⧁
ᙹᯩʑভྙᯕ݅. ᙹ⊹༉ߙᨱᱢᬊ⩥ᰆ᳑Õŝ࠺ᯝ⦽ḡ⊖ᮥ
༉ᔍ⦹۵äᯕaᰆၵ௭Ḣ⦹ḡอ, ⩥ᰆ᳑Õᮥəݡಽ༉ᔍ⦽Ğᬑ
᪡॒aᩕᱥࠥࠥ⪹ᔑᮥᱢᬊ⦽Ğᬑ, ⧕ᕾđŝ᮹₉ᯕaÑ᮹
ᨧᮭᯕ⪶ᯙࡽၵ, ᖅĥᱢšᱱᨱᕽᱽࡹŁᯩ۵Eq. (5)ෝ༉ߙᨱ
ᱢᬊ⦹ᩍࠥ ⧕ᕾ đŝᨱ۵ ⓑ ᩢ⨆ᯕ ᨧᮥ äᮝಽ ❱݉ࡽ݅.
Ł
ƃƏá ć
ā
Ƈ á Î ƌƂ
Ƈā
Ƈ á Î(5)
Fig. 2. Different Types of Heat Exchanger
Fig. 3. Coupled Process Between Convective and Conductive Heat Transfer at Heat Exchanger Wall
Table 2. Heat Transfer Rate, Average Fluid Temperature and Thermal Resistance (Elapsed Time: 96 hours)
Heat exchanger
aq (W/m)
bTf,m
()
cRb,m
(mK/W)
U Type 42.15 29.57 0.19
W Type 49.45 29.50 0.14
3U Type 51.68 29.48 0.12
aHeat transfer rate at steady state
bMean fluid temperature
cAverage borehole thermal resistance
Table 3. Dimensions of Energy Piles and Total Length of Heat Exchanger
Dimensions of Energy piles[m]
Total length of heat exchanger [m]
Heat exchanger
aDgrout b
DPHC single Case 1 Case 2
U 0.24 0.4 27.13 54.26 135.7
W 0.24 0.4 44.83 89.67 224.15
3U 0.24 0.4 63.49 126.98 317.45
aInner diameter of PHC
bOuter diameter of PHC
Fig. 4. Finite Element Model for Simulation and Heat Exchanger’S Type Used in Model
PHC ั૾ᮡĞ400mm, ԕĞ240mm, ʙᯕ13.75mಽᖅᱶ
⦹ᩡŁ, ᙹ⊹༉ߙᨱ ᱢᬊࡽ ḡၹ, PHC ั૾, ᩕ Ʊ⪹ ❭ᯕ⥥, ᙽ⪹ᙹ॒᮹ᔢᖙྜྷᖒ⊹۵Table 1ᨱ᧞⦹ᩍᱶญ⦹ᩡ݅. ḡၹ᮹
ᩕᱥࠥࠥ۵ᝅ⨹ᮥ☖⧕ᩕᱥࠥࠥߑᯕ░ᄁᯕᜅෝǍ⇶⦹ᩍ(Hukseflux ᔍ᮹TP-08ᮥᯕᬊ) ᇩ⡍⪵☁᪡⡍⪵☁ᨱݡ⦽ᩕᱥࠥࠥෝᔑᱶ⦹
ᩡŁ, ູ✙əᬑ✙, PHC ❭ᯝ, PB ❭ᯕ⥥, əญŁᙽ⪹ᙹ᮹
ྜྷᖒ⊹۵ šಉ ྙ⨭ᮥ ₙ᳑⦹ᩡ݅(Jeong et al., 2010; Park et
al., 2013).
Fig. 4 ۵ᩕᖒ܆⨹᮹ဍ౩ᯕᖹᮥ᭥⦽ᮁ⦽ᗭ༉ߙŝ
ᩕƱ⪹ʑ⩶┽(Fig. 2 ₙ᳑) ၰ႑⊹ෝᅕᩍᵡ݅. ᮁ⦽ᗭ༉ߙᮡ
Free tetrahedral ĊᯱᯕᔍᬊࡹᨩŁ, ᩕƱ⪹ʑᄞ໕᮹Ċᯱᗭ
⩶ᖒᮡ COMSOL ⥥ಽəఉ᮹ Pipe flow ༉ऩᨱ ԕᰆࡽ wall layer ʑ܆ᮥᯕᬊ⦹ᩡ݅. ᙽ⪹ᙹ᮹⚍᯦᪉ࠥ۵30ⳃ, ḡၹ᮹᪉ࠥ
۵17ⳃ, ᙽ⪹ᙹ᮹ᮁᗮᮡ0.8m/sಽᖅᱶ⦹ᩡ݅. ั૾ԕᇡᨱᖅ⊹
(a) Heat Efficiency of Pile
(b) Thermal Resistance of Pile
Fig. 5. Thermal Behavior According to the Variation of Thermal Conductivity of Soil
ࡽᩕƱ⪹ʑ᮹᳦ඹ۵U-Type, W-Type, 3U-TypeᮝಽǍᇥ⦹ᩡ
ᮝ໑, Ǒั૾႑⊹۵Case 1ŝCase 2᮹ࢱĞᬑෝᖅᱶ⦹ᩡ݅.
ᨱթḡ❭ᯝ᮹ȽĊၰᩕƱ⪹ʑ᮹ⅾʙᯕ۵Table 3ᨱ⦹ᩡ݅.
əญŁᬕᬊႊჶᨱᩑᗮa࠺(96eᩑᗮ)ŝᇡᇥa࠺(8e
a࠺, 16e⮕ḡ)ᮝಽǍᇥ⦹ᩍⅾ140e᮹݉ʑe⧕ᕾᮥ
ᙹ⧪⦹ᩡ݅.
3. ᨱթḡ❭ᯝᩕÑ࠺᮹ᩢ⨆ᯙᯱ
3.1 ச࣡ࢱଭવୢܑܑࢫવ֗ฅ׆ଭ෴ݗࠛવ Ջܛ
ᨱթḡ❭ᯝᮥ ᯕᬊ⦽ ḡᵲᩕƱ⪹ ᜅ▽ᨱᕽ ᙽ⪹ᙹ ᪉ࠥa
ᱶᔢᔢ┽ᨱࠥݍ⦹íࡹ໕ᙽ⪹ᙹ⠪Ɂ᪉ࠥ᪡❭ᯝᄞ໕᮹᪉ࠥ₉ a ᩕ Ʊ⪹ᮉᨱ እಡ⦹۵ Ğ⨆ᮥ aḡ۵ߑ, ᯕভ᮹ እಡᔢᙹ۵
ᨱթḡ❭ᯝ᮹ ᩕ ᱡ⧎ᮝಽ ᱶ᮹a ࡽ݅.
«
ƀá ć Ə
Þ
Ƅà
ƀß
(6)
ᩍʑᕽ
Ƅ۵ᙽ⪹ᙹ⠪Ɂ᪉ࠥ(ⳃ)
ƀ۵PHC ❭ᯝᄞ໕ᨱᕽ᮹
᪉ࠥ(ⳃ), Ə ۵ᩕƱ⪹ᮉ(W/m)ᮥӹ┡ԙ݅. ᯕ౨íᔑᱶࡽᨱթḡ
❭ᯝ᮹ᩕᱡ⧎ŝᩕƱ⪹ᮉᮡḡᵲᩕƱ⪹ᜅ▽᮹⧖ᝍᱢᖅĥ
ᗭŁ⧁ᙹᯩ݅. ᷪ, ᩕᱡ⧎ŝᩕƱ⪹ᮉ᮹ᱶ⪶⦽ᔑᱶᯕ
ḡᵲᩕ ᜅ▽᮹ ⧊ญᱢᯙ ᖅĥෝ čᯙ⦹í ࡽ݅.
ḡᩕ ᨱթḡ❭ᯝᮡ Ⓧí PHC ❭ᯝŝ ᩕ Ʊ⪹ʑ, əญŁ ə
ᔍᯕෝ₥ᬭᵝ۵ᗮ₥ᬡᰍಽǍᖒࡹ۵ߑ, ᯝၹᱢᮝಽᨱթḡ❭ᯝ ᮹ ᩕ ᱡ⧎ᨱ ᩢ⨆ᮥ ᵝ۵ ᵝࡽ ᯙᯱ۵ ᩕ Ʊ⪹ʑ᮹ ႑⊹᪡ ᗮ
₥ᬡᰍ᮹ ᩕᱥࠥࠥಽ ǎ⦽ࡽ݅Ł ಅᲙ ᯩ݅(Incropera and Dewitt, 2002). ᯕ۵ᨱթḡ❭ᯝ᮹ᩕᱡ⧎ᮡั૾᮹ԕᇡᱢᗭᨱ อᩢ⨆ᮥၼᮥᐱ, ั૾ᮥࢹ్Łᯩ۵ḡၹ᮹ᩕᱥࠥࠥ᮹ᩢ⨆ᮡ
ၙၙ⦹݅Ł❱݉⦹۵äᯕ݅. ʑ᳕ᩑǍᯱॅᯕŁಅ⦽ḡၹ᮹ᩕᱥ
ࠥࠥsᮡ1.5~3 W/mKಽᕽ, ᯕჵ᭥ԕᨱᕽḡၹ᮹ᩢ⨆ᮡᝅᱽಽ
ၙၙ⦹݅(Du and Chen, 2011; Ozudogru et al., 2012; Sagia et al., 2012). ə్ӹᝅᱽḡၹ᮹ᩕᱥࠥࠥ۵ḡၹ᮹᳑Õᨱ
ᄡ࠺ᖒᯕ⍅ḩᙹᯩ۵ߑᖅĥᯱ᮹᯦ᰆᨱᕽᯕ్⦽ᱱᮥeŝ⦹ʑ
ᛞ݅. ᅙᩑǍ۵ᙹ⊹༉ߙᮥ☖⦹ᩍḡၹ᮹݅᧲⦽ᩕྜྷᖒᨱෙ
ᜅ▽ᩕƱ⪹ᮉŝᩕᱡ⧎ᨱݡ⦽bb᮹ᄡ⪵᧲ᔢᮥᔕ⠕ᅕᦹ݅.
Fig. 5(a) ᪡zᯕᯝᱶeᯕḡӹᩕ⠪⩶ᔢ┽ᨱࠥݍ⦹íࡹ໕
ᜅ▽᮹ᩕƱ⪹ᮉࠥÑ᮹ᯝᱶ⦽sᮝಽᙹಕ⦹۵᧲ᔢᮥᅕᯕí
ࡽ݅. ḡၹ᮹ᩕᱥࠥࠥ᮹ჵ᭥ෝ1.2~2.6 W/mK ಽᄡ⪵┅໑
⧕ᕾᮥᙹ⧪⦽đŝ, ᩕƱ⪹ᮉᐱᦥܩ❭ᯝ᮹ᩕᱡ⧎ࠥ₉ᯕෝ
ᅕᯥᮥ ⪶ᯙ⧁ ᙹ ᯩᨩ݅(Fig. 5(b)).
⦽⠙, ḡᵲᩕƱ⪹ ᜅ▽ᨱ ᔍᬊࡹ۵ ᩕ Ʊ⪹ʑ᮹ ᮁ⩶ᨱ۵
U-Type, W-Type, 3U-Type ॒ᯕᯩᮝ໑, ᙹḢၡ⠱⩶᮹Ğᬑ
U-Type ᯕaᰆձญᔍᬊࡹŁᯩ݅. ⦹ḡอ↽ɝॅᨕᨱթḡ❭ᯝ ᮹ ᙹa ۹ᨕԉᨱ W ၰ 3U-Type᮹ ᩕ Ʊ⪹ʑ ᔍᬊᯕ
ኩჩ⧕ḡŁᯩ݅. ᯕॅᩕƱ⪹ʑ۵U-Typeᨱእ⧕ᕽๅḩŝ᮹
ᩕᱲⅪ໕ᱢᯕմᨕṈᮡั૾ʙᯕᨱᕽࠥᩕƱ⪹⬉ᮉᮥ᷾ݡ┍
ᙹᯩ݅. Fig. 6ᮡFig. 1ᨱࠥࡽḡၹ᳑Õ(ḡ⦹ᙹ᭥4.5m)ᨱ
ݡ⦽ ᩕ Ʊ⪹ʑ ᮁ⩶ ᄥ ᩕ Ʊ⪹ᮉŝ ᙽ⪹ᙹ ⠪Ɂ᪉ࠥ᮹ ᄡ⪵
᧲ᔢᮥᅕᩍᵡ݅. 96eĞŝᱶᔢᔢ┽ᨱÑ᮹ࠥݍ⦹໑, əভ ᮹ᩕƱ⪹ᮉᮡU-Typeᯕ᧞42 W/m, W ၰ3U-Typeᯕbb
49 W/m᪡52 W/mಽӹ┡ԍ݅. ၹ໕, ᯦⇽Ǎᙽ⪹ᙹ⠪Ɂ᪉ࠥ(ᮁ
᯦᪉ࠥ: 30ⳃ)۵bb29.57ⳃ, 29.50ⳃ, 29.48ⳃಽᕽU-Typeᨱ ᕽaᰆ׳íӹ┡ԍ݅. ᯕ۵ᩕƱ⪹ᮉᯕᔢݡᱢᮝಽԏᮡU-Type ᯕ᯦⇽Ǎ᪉ࠥ₉ෝaᰆᱢíอॅʑভྙᯕ݅. ੱ⦽Eq. (6)᮹
šĥᨱ᮹⧕ᕽᔑᱶࡽ❭ᯝ᮹ᩕᱡ⧎sᮡU-Typeᯕ᧞0.19
m·K/W, W ᪡3U-Typeᯕbb0.14 m·K/W, 0.12 m·K/Wᮝಽ
(a) Heat Transfer Rate
(b) Average Fluid Temperature
Fig. 6. Heat Transfer Rate and Average Fluid Temperature for Different Heat Exchanger Types
(a) U-Type
(b) W-Type
(c) 3U-Type
Fig. 7. Heat Transfer Rate for Different Ground Conditions (Saturated, Dry)
ᙹಕ⦹ᩡ݅(Table 2). ᯝၹᱢᮝಽ ᅕᨕ⪡ ԕᇡ᮹ ᩕᬱᯕ PHC ᄞ໕ᨱaʭᯕ᳕ᰍ⧁ᙹಾᗮ₥ᬡᰍᨱ᮹⦽ᩕᗱᝅᯕᱢᨕᲙᕽ
❭ᯝ᮹ᱥℕᩕᱡ⧎ᮡԏᦥḡíࡽ݅. U-Typeᮡᩕᬱᯕᅕᨕ⪡
ᵲᝍᨱ༑ಅᯩ۵ၹ໕Wӹ3U-Type ᮡᩕᬱᯕPHC ᄞ໕aʭᯕ
ᇺᨕᯩʑভྙᨱᩕᬱᱲⅪ໕ᱢ᷾a᪡ᇩᨕᔢݡᱢᮝಽU-Type ᅕ݅ԏᮡᩕᱡ⧎ᮥӹ┡ԕ۵äᮝಽᔍഭࡽ݅. ⧕ᕾđŝෝ
☖⧕ᕽ۵3U-Type ᩕƱ⪹ʑ᮹⬉ᮉᯕaᰆᳬ݅Ł❱݉⧁ᙹ
ᯩḡอ, ᝅᱽḡၹ᳑ÕᨱᕽᩕƱ⪹ᮉ᮹ᄡ࠺ᯕၽᔾ⧁ᙹࠥ
ᯩŁ, ੱ Ğᱽᱢᯙ ⊂໕, Ŗᔢ᮹ ᩍÕ ॒ᮥ Łಅ⧕ ⦹အಽ
ᖅĥᯱ᮹❱݉ᨱᕽᱢᱩ⦽ᩕƱ⪹ʑ᮹ᖁ┾ᯕᯕᨕᲙ
⦽݅.
Fig. 7۵ḡၹᯕ᪥ᱥÕ᳑ᔢ┽ᯝĞᬑ(ᩕᱥࠥࠥ0.25 W/mK)
᪡᪥ᱥ ⡍⪵ᔢ┽(ᩕᱥࠥࠥ2.4W/mK)ᯝĞᬑ, ┡᯦ᄥᩕ⬉ᮉ᮹
₉ᯕෝӹ┡ԕŁ ᯩ݅. ḡၹᯕÕ᳑ᔢ┽ᯝĞᬑ, ┡᯦᮹᳦ඹᨱ
šĥᨧᯕᩕƱ⪹ᮉᯕእ⦽sᮝಽᙹಕ⦹ᩡḡอ, ḡၹᯕ⡍⪵ࡹ
໕┡᯦᮹᳦ඹᨱəᄡ⪵᧲ᔢᯕ݅íӹ┡ԍ݅. ᪥ᱥ⡍⪵☁
᮹Ğᬑ┡᯦ᄥᩕƱ⪹ᮉᮡ3U-Typeᯕ55 W/m, W-Typeᯕ
52 W/m, U-Typeᯕ44 W/mᮝಽӹ┡ԍ݅. ┡᯦ᄥ₉ᯕෝ
Fig. 8. Ratio of Heat Exchange Rate Between Saturated and Dry Condition (Steady State)
Fig. 9. Borehole Thermal Resistance for Different Ground Conditions (Saturated, Dry)
(a) U-Type
(b) W-Type
(C) 3U-Type
Fig. 10. Results of Thermal Performance Analysis for Different Operating Methods for 6 Days (Periodic Operation, Continuous Operation)
⪶⯩ Ǎᇥ⦹ʑ ᭥⧕ ⡍⪵/Õ᳑ ᩕᱥࠥࠥ እᨱ ݡ⦽ ᩕƱ⪹ᮉ
እෝFig. 8ŝzᯕࠥ⦹ᩡᮝ໑, ᱶᔢᔢ┽ᨱᕽᩕƱ⪹ᮉእෝ
እƱ⧕ᅝভU-Typeᨱᕽ3U-TypeᮝಽiᙹಾᩕƱ⪹ᮉᯕḡၹ ᮹⡍⪵ࠥᨱၝq⦹íၹ᮲⦽݅۵äᮥ⪶ᯙ⧁ᙹᯩᨩ݅. ᯕ۵
ᩕᬱ᮹ᇥ⡍aḡၹaʭᯕฯᯕᇥ⡍⧁ᙹಾ(əᬑ✙ᨱ᮹⦽ᩕ
ᱡ⧎ᯕqᗭ⧁ᙹಾ) ᵝᄡḡၹ᮹ᩕᱥࠥࠥaᨱթḡ❭ᯝ᮹ᩕ⬉ᮉ ᨱၙ⊹۵ᩢ⨆ᮡ⍅ḡʑভྙᯙäᔍഭࡽ݅. Fig. 4ᨱࠥࡽ
ၵ᪡zᯕU-typeᨱᕽ3U-typeᮝಽiᙹಾᵝᄡḡၹᨱaʭᬕ
ᩕᬱ᮹ᙹa᷾a⦹íࡹ۵ߑᵝᄡḡၹ᮹ᩕᱥࠥࠥa׳ᮥĞᬑ,
ᩕᬱᮝಽᇡ░᮹ᩕᯕᵝᄡḡၹᮝಽᛞí⪶ᔑᯕࡹ໑, ᩕᬱᯕḡၹ
aʭᯕ ฯᯕ ᇥ⡍⧁ ᙹಾ ⪶ᔑ ᱶࠥ۵ ⍅ḡí ࡽ݅. ᕽ
U-typeᨱᕽ3U-typeᮝಽiᙹಾᩕ⪶ᔑᯕ⍅ḡŁᩕƱ⪹ᮉᯕ
᷾a⦹íࡽ݅. ၹ໕ᵝᄡḡၹ᮹ᩕᱥࠥࠥaԏᮥĞᬑ, ᩕᬱᇥ⡍ᨱ
ᔢšᨧᯕᩕ⪶ᔑᮡᅕᨕ⪡ԕᇡᨱᕽᱶℕࡹ໑, ᩕƱ⪹ʑTypeᨱ
ᔢšᨧᯕԏᮡᩕ⬉ᮉᮥӹ┡ԕíࡽ݅. ੱ⦽Eq. (6)ᮥᯕᬊ⧕ᕽ
ḡၹ᮹⡍⪵ࠥᨱෙ┡᯦ᄥᩕᱡ⧎ᮥᔑᱶ⦹ᩍFig. 9ᨱࠥ⦹
ᩡ݅. ᵝᄡḡၹᩕᱥࠥࠥᨱ❭ᯝ᮹ᩕᱡ⧎ᯕ݅íӹ┡ӹ ໑, ᯕෝḡၹ᮹⡍⪵ᩍᇡᨱݡ᯦⦹໕3U-Type᮹Ğᬑ, ⡍⪵☁᪡
Õ᳑☁ᨱᕽ ᧞ 8.7%᮹ ᩕ ᱡ⧎ ₉ᯕෝ ᅕᩡ݅.
Fig. 11. Configuration of Piles Used in the Simulation Model (D:
Separation Distance)
Fig. 12. Isotherm Showing the Thermal Interference Between Two Energy Piles
3.2 ࢺ࣑ݗࠛવՋܛ
Ǎ᳑ྜྷษ݅ᔍᬊᇡ⦹a݅ʑভྙᨱbb᮹ᇡ⦹ෝ∊᳒⍽
ᵝ۵a࠺eᯕǍࡹḡอ, ᯝၹᱢᮝಽḡᵲᩕᜅ▽ᮡᵝe
8e᮹a࠺, e16e⮕ḡಽᬕᬊ⦹Łᯩ݅. ᯕ్⦽ᇡᇥa࠺
ᮥ ☖⦹ᩍᩕᬱᨱ ᮹⧕ ᔢࡹᨩḡၹ᮹ ᪉ࠥ۵ ݅ᬱ௹᮹
ᔢ┽ಽ⫭ᅖ⦹íࡹ໑, ᰆʑÑ࠺ᨱᕽӹ┡ԁᙹᯩ۵ḡၹ᮹ᩕ
⇶ᱢ⩥ᔢᮥႊḡ⦹ᩍᱥℕ⬉ᮉᮥᮁḡ⧁ᙹᯩíࡽ݅. ə్ӹ
⮕ḡʑeᨱḡၹ᮹᪉ࠥa᪥ᱥ⯩⫭ᅖࡹ۵äᯕᦥܩʑভྙᨱ
ᇡᇥa࠺᮹Ğᬑᨱࠥᨕ۱ᱶࠥᩕ⬉ᮉᱡ⦹aၽᔾ⦹ḡอ, ᩑᗮa
࠺ᨱ እ⧕ᕽ۵ ə ᱶࠥa ၙၙ⦹݅Ł ᅝ ᙹ ᯩ݅.
Fig. 10 ᮡ 6ᯝe᮹ ᩑᗮa࠺ ၰ ᇡᇥa࠺ ᮹ ᩕ ᖒ܆⨹
đŝෝ ᅕᩍᵡ݅. U᪡ W, əญŁ 3U-Type᮹Ğᬑ, ↽Ⅹ a࠺
8 e⬥᮹ᩕƱ⪹ᮉᮡbb59 W/m, 76 W/m, 84 W/m ᯕŁ, 6ᯝṙa࠺8e⬥᮹ᩕƱ⪹ᮉᮡᇡᇥa࠺bb51 W/m, 61 W/m, 63 W/m, ᩑᗮa࠺bb41 W/m, 48 W/m, 51 W/m ᯕ݅. ᷪ128eĞŝ⬥ᬕᬊႊჶᨱU-Typeᮡ᧞
19%, W-Type ᮡ᧞21%, 3U-Typeᮡ᧞19%᮹₉ᯕෝᅕᩡᮝ໑, ᰆʑᱢÑ࠺ᮝಽiᙹಾⓑ₉ᯕෝӹ┡ԝäᮝಽᩩᔢࡽ݅.
┡᯦ᄥಽḡᵲ᪉ࠥ᮹⫭ᅖᱶࠥ₉ᯕaᨕ۱ᱶࠥၽᔾ⦹۵äᮝಽ
ᔍഭࡹ۵ၵ⇵⬥݅᧲⦽ᱲɝᮥ☖⧕əᬱᯙᮥᇥᕾ⧕ᅝ⦥ᖒᯕ
ᯩ݅. ࢱaḡᬕᬊႊჶ༉ࢱᩕ⇶ᱢ⩥ᔢᯕ⦥ᩑᱢᮝಽၽᔾ⦹ḡ อ, ǎԕ᮹Ğᬑ, ᩍ℁Ԫႊᇡ⦹ಽᯙ⧕ḡၹᨱ⇶ᱢࡽᩕᨱթḡa
ĉᬙ℁ӽႊᇡ⦹ಽᔢᘥࡹᨕᩑᵲᩕ⬉ᮉᮡÑ᮹ᯝᱶ⦹íᮁḡࢁ
ᙹࠥ ᯩ݅.
3.3 ֞࠱ތଭવԩথ
ݡ⩶Ǎ᳑ྜྷ᮹ʑⅩ۵ᯝၹᱢᮝಽǑั૾⩶┽ᯕ໑, əᵲ᮹
ᯝᇡᇥᮥᖁᄥ⦹ᩍᨱթḡ❭ᯝᮥŖ⦹íࡽ݅. ᯕভʑⅩ᮹Ǎ᳑
ᱢᯙᦩᱶᖒᯕᅕᰆࡹ۵࠺ᨱᔍᬊᯱa⦥ಽ⦹۵ᩕ⬉ᮉᮥ
อ᳒┅۵↽ᱢ᮹႑⊹a⦥⦹݅. əญŁᯙᱲ⦽ᨱթḡ❭ᯝe ᨱ۵ᔢ⪙ᩕeᖎ⩥ᔢᯕ⦥ᩑᱢᮝಽၽᔾ⦹íࡹ໑, ᯕäᮡᰆʑᬕ ᬊᮝಽ iᙹಾ ᱥℕ ⬉ᮉᨱ ⓑ ᩢ⨆ᮥ ӝ⊹í ࡽ݅. ᅙ ᩑǍ۵
ᖅĥ݉ĥᨱᕽᇡ░ᯕ్⦽ᩕeᖎᮥ↽ᗭ⪵┍ᙹᯩ۵ႊᦩᯕ
⦥⦹݅Ł❱݉⦹ᩍ, ᨱթḡ❭ᯝ᮹↽ᱢ႑⊹ၰั૾e↽ᗭ
ᯕĊÑญෝᱽ⦹Łᯱ⦹ᩡ݅. ᩕƱ⪹ʑ᮹ᮁ⩶ᮡⓍíU-Type, W-Type əญŁ3U-TypeᮝಽǍᇥ⦹ᩡᮝ໑, Ǒั૾႑⊹۵Case 1 ŝCase 2ಽᖅᱶ⦹ᩍᕽ, bCase ᄥᯕĊÑญෝᔑᱶ⦹ᩡ݅.
ᯕভᯕĊÑญ(D)۵ᯙᱲ⦽ั૾᮹ၵˆᄞ໕ᔍᯕ᮹ÑญŁ
ᱶ᮹⦹ᩡ݅(Fig. 11). ᯝၹᱢᮝಽᨱթḡ❭ᯝ᮹ᬕᬊᮡᇡᇥa࠺(8
ea࠺, 16e⮕ḡ)ᮝಽᯕᨕḡḡอᅕᙹᱢᯙᖅĥෝ᭥⧕
ᬕᬊ⩶┽۵ 96e ᩑᗮa࠺ᮝಽ ⧕ᕾᮥ ᙹ⧪⦹ᩡ݅.
Fig. 12᪡zᯕzᯕࢱ}᮹ᨱթḡ❭ᯝᔍᯕ᮹Ñญaaʭᬭḱ
ᨱeᖎ⩥ᔢᮡ⦥ᩑᱢᮝಽᯝᨕӹ໑, ᯕಽᯙ⧕ၽᔾ⦹۵
ᨱթḡ❭ᯝ᮹ᩕ⬉ᮉᱡ⦹ෝeŝ⧁ᙹᨧ݅. ᕽFig. 14᪡
zᯕᯕĊÑญᨱෙeᖎᨱ᮹⦽ᩕƱ⪹qᗭᮉᮥӹ┡ԕᨕ, eᖎᮥ↽ᗭ⪵⦹۵↽ᱢᯕĊÑญෝᔑᱶ⦹Łᯱ⦹ᩡ݅. ੱ⦽Fig.
13ᮡḡၹ᮹⡍⪵ࠥaǑั૾᮹ᩕeᖎᨱၙ⊹۵ᩢ⨆ᮥᅕᩍᵝŁ
ᯩ݅. ḡၹᯕ⡍⪵☁ᯙĞᬑ, Ⅹၹᇡᨱ۵ᄥ݅ෙ₉ᯕෝᅕᯕḡ
ᦫḡอ, ᰆʑÑ࠺ᮝಽiᙹಾǑั૾ᨱ᮹⦽ᩕeᖎ⩥ᔢᯕࢱऽ్
ḡíӹ┡ӽ݅. ᯕ۵ᩕᬱ᮹ᨱթḡaᨱթḡ❭ᯝᵝᄡ᮹ḡၹᮝಽ ʭḡ⇶ᱢࡹʑʭḡ۵ᯝᱶeᯕᗭࡹ໑, əeᮡ↽ᗭ⦹
ᯕᔢᯥᮥᙹᯩ݅. ၹ໕, ḡၹᯕÕ᳑☁ᯙĞᬑ, ᩕƱ⪹ʑ┡᯦ᨱ
ᔢšᨧᯕ༉ु Ğᬑᨱ ݡ⧕ᕽᩕ eᖎ ⩥ᔢᯕ⩥ᱡ⯩ ᵥᨕॅí
ࡽ݅. ᯕ۵ᵝᄡḡၹᯕÕ᳑⧁Ğᬑ, ᩕᬱᨱ᮹⦽ᵝᄡḡၹᮝಽ᮹
(a) U-Type (b) W-Type
(c) 3U-Type
Fig. 13. Decrease of Heat Transfer Rate by a Thermal Interference
(a) U-Type, Case 1 (b) U-Type, Case 2 (c) W-Type, Case 1
(d) W-Type, Case 2 (e) 3U-Type, Case 1 (f) 3U -Type, Case 2
Fig. 14. Decrease of Heat Transfer Rate by a Separation Distance
Table 4. Separation Distance for Different Heat Exchangers
Decreasing rate (%) (separation distance=2.75D)
Separation distance (Decreasing rate of q less than 1%)
Heat exchanger Case 1 Case 2 Case 1 Case 2
U 1.1% 1.8% 2.8D 3.2D
W 1.5% 2.8% 3.1D 3.6D
3U 1.8% 2.9% 3.4D 3.7D
Table 5. Decrease of Heat Transfer Rate for a Group Pile (96-hour Operation)
Heat exchanger Single Case 1 Case 2
q q *쨣q q *쨣q
U 42.251 41.786 0.465 41.476 0.755
W 49.543 48.782 0.760 48.170 1.373
3U 52.876 51.945 0.932 51.360 1.516
*Variance of heat transfer rate compared to single configuration
