Effects of air gap on insulation thickness and life cycle costs for different pipe diameters in pipeline

Daşdemir, Ali; Ertürk, Mustafa; Keçebaş, Ali; Demircan, Cihan

doi:10.1016/j.energy.2017.01.125

Cited by 22 publications

(9 citation statements)

References 28 publications

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“…Using the degree day method, the annual energy amount transferred by fluid within the pipe with the heating process is assumed to be equal to the annual heat losses from within the pipe to the external environment, and it may be generally expressed as :

Q_{normalp, loss} = 86, 400 HDD U_{p}

where U p is the total heat transfer coefficient for all pipe layers. For Case 1, with uninsulated pipe layers (internal fluid + pipe + external fluid) and Case 2 with air gapped and insulated pipe layers (internal fluid + pipe + air gap + insulation material + external fluid), the total heat transfer coefficients are given below :

\frac{1}{U_{p, un - ins}} = \frac{1}{h_{i} A_{i}} + \frac{\ln ((), \frac{r_{1}}{r_{0}})}{2 π {Lk}_{p}} + \frac{1}{h_{o} A_{o}}

and

\frac{1}{U_{p, ag - ins}} = \frac{1}{h_{i} A_{i}} + \frac{\ln ((), \frac{r_{1}}{r_{0}})}{2 π {Lk}_{p}} + + \frac{\ln ((), \frac{r_{2}}{r_{1}})}{2 π {Lk}_{ag}} + \frac{\ln ((), \frac{r_{3}}{r_{2}})}{2 π {Lk}_{ins}} + \frac{1}{h_{o} A_{o}^{'}}

where A is heat transfer surface area of the pipe, A i = 2 π L r 0 , A o = 2 π L r 1 , and

A_{o}^{'} = 2 π L r_{3}

. In the pipe layer, the convection heat transfer coefficients for the internal and external environments can be calculated as follows :…”

Section: Discussionmentioning

confidence: 99%

“…The annual total energy cost, C f , and total cost of insulation material, C ins , for heat losses occurring in the pipe with insulation applications are determined as follows :

C_{f} = m_{f} C_{F}

and

C_{ins} = C_{I} V

where C F is unit cost of any fuel as $/kg, $/m 3 , $/kWh, C I is cost of insulation material per unit volume as $/m 3 and

V = π (r_{3}^{2} - r_{2}^{2}) L

as m 3 .…”

Section: Discussionmentioning

confidence: 99%

“…In conclusion, according to LCC analysis, the total cost, C t , and energy savings, S , for insulated pipes with air gap may be calculated below :

C_{t} = P_{1} C_{f} + P_{2} C_{ins}

and

S = P_{1} C_{f}^{'} - P_{2} C_{ins}

where

C_{f}^{'}

is the different between energy cost for the un‐insulated (Case 1) and insulated pipes with air gap (Case 2).…”

Section: Discussionmentioning

confidence: 99%

“…To calculate optimum insulation thickness, the differential of the annual total cost, C t , in Equation is taken according to the external diameter, r 3 , of the pipe layer, and then the obtained result is brought to zero. The r ins,opt value in Equation may be found using MATLAB optimization Toolbox .

0 = - \frac{86, 400 P_{1} HDD C_{f} ((), \frac{1}{k_{ins} r_{ins, opt}} - \frac{1}{h_{o} {r_{ins, opt}}^{2}})}{H_{u} η_{hs} {(\frac{1}{h_{i} r_{0}} + \frac{\ln (\frac{r_{1}}{r_{0}})}{k_{pipe}} + \frac{\ln (\frac{r_{2}}{r_{1}})}{k_{ag}} + \frac{\ln (\frac{r_{ins, opt}}{r_{2}})}{k_{ins}} + \frac{1}{h_{normalo} r_{ins, opt}})}^{2}} + 2 P_{2} C_{ins} r_{ins, opt}

…”

Section: Discussionmentioning

confidence: 99%

“…As far as studies on the use of insulation and air gap to reduce heat loss in pipelines are concerned, in the open literature, only one study, which has been recently performed by the authors investigated the effects of air gap on insulation thickness and life cycle costs for different diameter steel pipes. The results of their study indicated that in terms of the effect of air gap on insulation thickness and life cycle costs, for small diameter pipes air gap was effective, whereas for large diameter pipes the insulation thickness played significant role.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Sensitivity Analysis of Optimum Insulation Thickness for Pipe Diameters in Pipe Insulation with Air Gap for City Pipelines

Ural

Daşdemir

Keçebaş

2019

Env Prog and Sustain Energy

Self Cite

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The use of effective insulation methods to reduce heat loss and minimize its economic and environmental effects in city piping systems is an important topic globally. This study uses a new method for insulation of city piping systems of an air gap around pipelines and optimizes the thickness of insulation for the pipe. With this aim, a mathematical model based on heat degree days and life cycle cost analysis is used. Thus, according to the insulation thickness, air gap and pipe diameter values, the objective functions of optimum insulation thickness, energy cost savings, and payback period are comparatively assessed. The results indicate that using an air gap causes an 89% and 57% fall in optimum insulation thickness values for small and large diameter pipes, respectively. Additionally, sensitivity analysis was completed for the objective functions in terms of parameters such as interest rate, discount rate, life span, unit cost of fuel, cost of insulation material per unit volume, heat degree day, and air gap values. Based on the study methodology, life span, air gap, and unit fuel cost parameters were shown to have a significant effect on the objective functions. When insulation with air gap is applied, together with reducing the optimum insulation thickness at least 72% (from 0.009 to 0.031 m), it increases energy cost savings at 74% (from 5.47 to 21 $/m‐yr) for large diameter pipes and reduces the payback period at 78% (from 0.1 to 0.04 yr‐m) for small diameter pipes. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

show abstract

Q_{normalp, loss} = 86, 400 HDD U_{p}

\frac{1}{U_{p, un - ins}} = \frac{1}{h_{i} A_{i}} + \frac{\ln ((), \frac{r_{1}}{r_{0}})}{2 π {Lk}_{p}} + \frac{1}{h_{o} A_{o}}

and

\frac{1}{U_{p, ag - ins}} = \frac{1}{h_{i} A_{i}} + \frac{\ln ((), \frac{r_{1}}{r_{0}})}{2 π {Lk}_{p}} + + \frac{\ln ((), \frac{r_{2}}{r_{1}})}{2 π {Lk}_{ag}} + \frac{\ln ((), \frac{r_{3}}{r_{2}})}{2 π {Lk}_{ins}} + \frac{1}{h_{o} A_{o}^{'}}

where A is heat transfer surface area of the pipe, A i = 2 π L r 0 , A o = 2 π L r 1 , and

A_{o}^{'} = 2 π L r_{3}

. In the pipe layer, the convection heat transfer coefficients for the internal and external environments can be calculated as follows :…”

Section: Discussionmentioning

confidence: 99%

“…The annual total energy cost, C f , and total cost of insulation material, C ins , for heat losses occurring in the pipe with insulation applications are determined as follows :

C_{f} = m_{f} C_{F}

and

C_{ins} = C_{I} V

where C F is unit cost of any fuel as $/kg, $/m 3 , $/kWh, C I is cost of insulation material per unit volume as $/m 3 and

V = π (r_{3}^{2} - r_{2}^{2}) L

as m 3 .…”

Section: Discussionmentioning

confidence: 99%

“…In conclusion, according to LCC analysis, the total cost, C t , and energy savings, S , for insulated pipes with air gap may be calculated below :

C_{t} = P_{1} C_{f} + P_{2} C_{ins}

and

S = P_{1} C_{f}^{'} - P_{2} C_{ins}

where

C_{f}^{'}

is the different between energy cost for the un‐insulated (Case 1) and insulated pipes with air gap (Case 2).…”

Section: Discussionmentioning

confidence: 99%

0 = - \frac{86, 400 P_{1} HDD C_{f} ((), \frac{1}{k_{ins} r_{ins, opt}} - \frac{1}{h_{o} {r_{ins, opt}}^{2}})}{H_{u} η_{hs} {(\frac{1}{h_{i} r_{0}} + \frac{\ln (\frac{r_{1}}{r_{0}})}{k_{pipe}} + \frac{\ln (\frac{r_{2}}{r_{1}})}{k_{ag}} + \frac{\ln (\frac{r_{ins, opt}}{r_{2}})}{k_{ins}} + \frac{1}{h_{normalo} r_{ins, opt}})}^{2}} + 2 P_{2} C_{ins} r_{ins, opt}

…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sensitivity Analysis of Optimum Insulation Thickness for Pipe Diameters in Pipe Insulation with Air Gap for City Pipelines

Ural

Daşdemir

Keçebaş

2019

Env Prog and Sustain Energy

Self Cite

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show abstract

Calculation of optimum insulation thickness of external walls in residential buildings by using exergetic life cycle cost assessment method: Case study for Turkey

Guven

2019

Env Prog and Sustain Energy

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Energy is one of the most fundamental event of the universe and it is impossible to imagine an area where energy is not used. The energy demand is also increasing with the ever‐increasing population of the world. We also use energy to meet our heating and cooling needs. Heat loss from the exterior walls of buildings is important, so thermal insulation on the wall is very critical. In this study, optimum insulation thickness is determined for four provinces and two different insulation materials selected from four different climatic regions of Turkey. In order to calculate insulation thicknesses, the number of the degree‐day and exergetic environmental impact factor have been used. Natural gas is used as fuel. By using exergetic life cycle cost assessment method for rock wool and glass wool as insulation materials, the changes of CO2 emission values, the environmental impact factor, and energy saving values are determined for optimum insulation thickness. The optimum insulation thickness, which are calculated by using the number of the degree‐day and exergetic environmental impact factor for glass wool and rock wool is 0.1103 m and 0.04375 m for Antalya, 0.1667 m and 0.07292 m for Isparta, 0.1667 m and 0.0625 m for Bursa, and 0.2188 m and 0.1021 m for Erzurum, respectively. The reduction of carbon dioxide emission values for glass wool and rock wool 86% and 64% for Antalya, 90% and 76% for Isparta, 92% and 82% for Erzurum, and 90% and 73% for Bursa, respectively. Net exergetic environmental impact saving values for glass wool and rock wool: 589 mPts/m2‐yr and 342 mPts/m2‐yr for Antalya, 1,318 mPts/m2‐yr and 642 mPts/m2‐yr for Bursa, 1,315 mPts/m2‐yr and 878 mPts/m2‐yr for Erzurum, and 2,248 mPts/m2‐yr and 1,687 mPts/m2‐yr for Isparta, respectively.

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Thermal Insulation for Refrigeration Pipe Made of Polyurethane Reinforced Coconut Husk and Rice Husk

Khalid,

Zuhri,

Hairuddin

et al. 2023

Springer Proceedings in Materials

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Effects of air gap on insulation thickness and life cycle costs for different pipe diameters in pipeline

Cited by 22 publications

References 28 publications

Sensitivity Analysis of Optimum Insulation Thickness for Pipe Diameters in Pipe Insulation with Air Gap for City Pipelines

Sensitivity Analysis of Optimum Insulation Thickness for Pipe Diameters in Pipe Insulation with Air Gap for City Pipelines

Calculation of optimum insulation thickness of external walls in residential buildings by using exergetic life cycle cost assessment method: Case study for Turkey

Thermal Insulation for Refrigeration Pipe Made of Polyurethane Reinforced Coconut Husk and Rice Husk

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