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Role of Infrared Thermography in Result Oriented Energy Audits – A Case Study Approach

Shashibhushan S Agrawal BEE Accredited Energy Auditor (AEA-0054)

BEE Certified Energy Manager & Auditor (EA-1090) ASNT Level II (Thermography, UT, MT, RT, LPT)

AEEE Consultancy Services E-mail :- shashi@aeeec.com ; Mobile :- 09422161638

www.aeeec.com

Introduction :- Apart from regular energy audit techniques, utilization of infrared thermography have resulted in excellent energy saving opportunities to the author. Energy losses like thermal insulation loss, loss due to faulty steam trap, phase imbalance in electrical system, loss in air conditioning system etc can be identified easily & accurately by using thermography. The energy saving opportunities in above stated losses are low hanging fruits which can be identified at marginal cost by infrared thermography. A good resolution thermal imaging camera, qualified thermographer with ASNT Level II certification results in identification of energy loss areas. Thermography is used by us during energy audit for different application –

1) Boiler/Furnace/Thermic Fluid Heater thermal insulation to assess the losses. 2) Steam Trap Survey to effectively monitor its health. 3) Various process equipment thermal insulation survey. 4) Explore Waste Heat Recovery options in various process. 5) Thermal infiltration & ex-filtration in various ducts. 6) Thermal ingress in air conditioning system. 7) Assisting for locating loss in substations. 8) Assisting for locating current/voltage imbalance locations in MCC Panels. 9) Identification of undersized cables from its temperature.

Introduction to Thermography :- Though traditionally it was believed that thermography (Thermal Imaging) is useful mainly for predictive maintenance, the case study presented in the paper will help to explain use of therography for improvement in energy efficiency. The aim of the paper is to explain why thermogrpahy to be integral part of energy audit. Any body above absolute zero (-273°C) emits infrared radiations, which can be captured by thermal imaging camera which later converts to image that can be seen & analyzed by human eye. The infrared rays are invisible to human eye as have higher wave length than visible light rays.

Name Wavelength Frequency (Hz) Gamma ray less than 0.01 nm more than 10 EHz

X-Ray 0.01 nm to 10 nm 30 EHz – 30 PHz

Ultraviolet 10 nm – 380 nm 30 PHz – 790 THz

Visible 380 nm – 700 nm 790 THz – 430 THz

Infrared 700 nm – 1 mm 430 THz – 300 GHz

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Microwave 1 mm – 1 meter 300 GHz – 300 MHz

Radio 1 mm – 100,000 km 300 GHz – 3 Hz

Gamma Rays

X-Rays

Ultraviolet Rays

Visible Rays

Infrared Rays

Microwave

Radio

Wave Length Value

Thermography is very useful for detecting the additional heat loss due to system problems. The comparison of normal heat loss pattern and additional heat loss pattern can be compared to diagnose the system problems such as bearing failures, thermal insulation failures, steam trap failures, phase imbalance in electrical system etc. Most of the Mechanical & Electrical System has allowable operating temperature limits, which can be used as guide line to determine the extent of loss. All mechanical & Electrical systems generate thermal energy during normal operation which allows Infrared Thermal Imaging to evaluate their operating condition. One of the biggest problems in mechanical systems is excessive temperatures. This excessive heat can be generated by friction, cooling degradation, material loss or blockages. An excessive amount of friction can be caused by wear, misalignment, over or under lubrication and misuse. While in electrical system excessive heat can be generated by current imbalance, looseness in connections, under sizing of conductors etc. Even latest IE3 or even IE4 efficiency level motor provided with imbalance electrical supply will result in unsatisfactory performance of these motors. Thermography provides quick diagnosis of problems, resulting in higher efficiency of electrical motors.

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The main focus of this paper is utilization of thermography for energy savings. I will present some cases where energy loss detected by thermography. The thermal losses can be co-related by experience with various system losses. The recommended thermography study pattern should be as given below –

Recommended System for Using Thermography for Energy Audits

The use of thermography in energy conservation / saving needs very systematic result oriented approach. The result depends not only on good thermal imaging camera but largely on thermographer who interprets thermal image properly co-relating the given variables of system under study. The experience & knowledge of thermographer is very important for analysis and reporting of thermography results. It is popular perception in Industry today that "Good Thermal Imaging camera is enough for Thermography". This perception many times leads to wrong interpretations due to which desired results & objectives of thermography are not achieved. The approach will be "Good Thermal Imaging Camera with Experienced & Qualified Thermographer is must for Result Oriented Thermography". The professional thermographer preferably ASNT Level II (American Society of Non Destruction Testing, Recommended Practice SNT-TC.1A, 2006 Edition) knows very well the effect of reflection, emissivity, distance, co-relation of image with give system parameter etc. Without sound knowledge & experience of these parameters, the interpretation of the thermal image may even result in undesirable results. The BEE Certified Energy Auditor should rely on the report of qualified & experience thermographer to judge the loss & possible remedies. Ideally it's always desirable that BEE Certified Energy should him self be good thermographer. The author him self is ASNT Level II thermographer along with BEE Certified Energy Auditor. Carried more than 500 Industrial energy audits & more than 100 Commercial Building Energy Audits. Also provided services to more than 100 Industries services as professional thermographer. Some of the case studies showing effective utilization of thermography for energy savings / audits are as given below-

Case Study -- Externally Good Looking but Faulty Paint Baking Booth Thermal Insulation

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The temperature inside the baking booth is maintained by LPG Fired HAG (Hot Air Generator) at 75°C. The ambient temperature in this case was 31°C. The externally good looking thermal insulated oven shows the unwanted thermal loss in thermal image. Preventing the thermal loss leads to LPG Savings.

Such Latent Thermal losses are very difficult to be assessed without thermography. These minor

& Latent losses results in substantial energy loss over the time span of one year resulting in higher Co2 emission.

Case Study – Good Insulation Material without Quality Workmanship

Though good material for insulation used, but improper workmanship at joints leads to thermal losses from Joints.

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The improved workman ship can save such thermal losses which in turn saves fuel. Even local corrective action at locations suggested by thermography report will result in reduction in energy losses.

Such Thermal losses are very difficult to be assessed without thermography. These minor & Latent losses results in substantial energy loss over the time span of one year resulting in

higher Co2 emission.

Case Study – Externally Normal Appearing Faulty Thermal Insulations

Deceptive externally normal appearing thermal insulations often accounts for substantial losses from thermal insulation. By using thermography even we can improve insulation by local repairs instead of complete replacement which will result in lower replacement cost. Some time it is observed that the hot spots on insulation are developed due to water seepages from some location, by arresting such problems and locally repairing the insulation will reduce further energy loss.

Such losses no doubt are practically very difficult to be identified & located without Thermography.

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Case Study – Highlighting the Existing Thermal Losses in Convincing Way

Often the most neglected portions of thermal insulation are pipe fittings & pipe joints. They loss from these location results in substantial energy loss.

Thermography Highlights such losses in Convincing way.

The extent of loss can be better explained to management after thermal imaging. Negligence often leads to huge energy loss. Thermal insulation is like a fine art in energy conservation. Low cost, no cost measure like stoppage of leakages & scientific thermal insulation leads to great energy saving.

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Case Study – Using Thermography to Locate Losses Remotely

Using thermography the un-insulated portions, heat losses can be identified from substantial distance. We have notified it as "Thermal Loss Scanning of Plant, Machinery & Equipments"

Even from substantial distance thermal leakages can be pointed out to save energy.

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These picture are self explanatory for showing importance of thermography for thermal leakages.

Thermal energy losses of any magnitude can be arrested with pin point accuracy using thermography.

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The thermal leakages from these latent areas results in considerable energy loss.

During energy audit, thermography is effectively used to detect the thermal losses easily. Even waste heat recovery opportunities can be explored.

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Case Study – Steam Trap Survey

The above is example of proper functioning of steam trap & below is example of faulty steam trap. We have found Thermography as one of the best way to carry steam trap survey. We have made steam trap survey as integral part of energy audit.

Case Study – Thermal Loss Detection from Air Conditioned Space from Outside

For air conditioned space, thermal leakages results in loss of electrical energy supplied to air conditioning system. We are very effectively using thermography for air conditioned space. Thermography carried from outside the air conditioned space gives vital information for energy savings.

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Case Study – Thermal Loss Detection from Air Conditioned Space from Inside

Thermography carried from inside the air conditioned space give the thermal ingress in to air conditioned space & helps to identify the heat load.

Without thermography the thermal ingress identification can become practically very difficult.

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Case Study – Electrical System Imbalance Diagnosis

Various problems related to power quality such as phase imbalance results in lower efficiency of electrical system along with premature failure as well. Thermography of selective supply line after finding phase imbalance during data logging often results in exact diagnosis of problem.

Case Study – Motor Loss Reduction by Early Detection of Problems

Hot spots on electrical motors due to various reasons such as bearing failure, misalignment results in hot spots on motor which along with other related problem results in higher motor losses & lower efficiency.

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References :- 1) Various Energy Audit Report by Author using Thermography. 2) Kaplan, Herbert : ASNT Level III Study Guide on Infrared & Thermal Testing Method 3) Case Studies for thermography from web site www.aeeec.com 4) Introduction to Thermography Principle by Fluke 5) Various presentation by Author for "Low cost No cost energy saving measures using

thermography." About Author :- Shashibhushan S Agrawal, is having degree in Mechanical engineering from Government college of engineering, Amravati (Maharashtra State) & has experience of more than 25 Years. He is BEE Accredited Energy Auditor (AEA-0054), BEE Certified Energy Manager & Auditor (EA-1090). He has received four consecutive Award for "Excellence in Energy Conservation & Management" under "Energy Auditor" Category by Government of Maharashtra. He has done ASNT Level II (Thermography, UT, MT, RT & LPT). He received advance training in MCDT techniques from JICA, Japan. He has completed "Change Project" in China, Sweden & India for Energy Conservation & Renewable energy. He has carried more than 500 Industrial Energy Audits & more than 100 Commercial building energy audits. He /his firms are panel energy auditor for MEDA, GEDA, MPUVN, PCRA, PFC Consulting Ltd.