Heat Pipe Automobile Radiator - A Proposal

AIM:  The aim of this project is to design and develop a heat pipe radiator for a 5-passenger automobile.

DURATION:  The project duration is 30 Months.

SHORT DESCRIPTION:  The radiator is an important element of the cooling system of an automobile. The radiator comes under the category of compact heat exchangers with large densely packed cooling plates added as extended surface to small diameter aluminum or copper cooling tubes. Radiator failures are very common due to overheating of the numerous welded or brazed joints between the cooling surface and the tubes. Heat pipe application to automobile radiator is a new concept which will drastically reduce or completely eliminate radiator tube failures besides substantially improving the radiator performance. Improved performance will result in reduced overall size of the radiator and thus contribute to reduced space requirements in today’s compact cars. The proposed project is aimed at the application of new technology to automobile radiators and demonstration of the many benefits in terms of reduced size, reduced materials requirements, reduced number of welded joints, reduced cost of equipment and improved performance.

DESIGN OF HEAT PIPE RADIATOR: The design of automobile radiator begins with selecting a suitable automobile engine and its cooling requirements. The various steps involved are,

1.      For the purpose of proving the new concept, choose a suitable automobile engine and determine its cooling requirements.

2.      Select the type of heat pipes, typically Copper-Water, Aluminum-Ammonia, and Aluminum-Acetone combinations and size the heat pipes to meet the cooling requirements.

3.      Determine the cooling surface area and the number cooling elements

4.      Determine the header sizes

5.      Assemble the cooling elements with heat pipes

6.      Assemble the heat pipes with the headers

7.      Make the radiator assembly ready for installation on a typical automobile engine for demonstration and long term operation for reliability and endurance

SCOPE OF PRESENT WORK: Present work envisages design, development and demonstration of a heat pipe radiator on a 5-passenger car. The work involves the following steps;

1.      Select a typical 5-seater car engine

2.      Determine its cooling requirements and radiator cooling capacity

3.      Select the type of heat pipe,

4.      Size the heat pipe dia., length, shape, materials, number etc. to meet the cooling requirements

5.      Manufacture/procure heat pipes

6.      Manufacture/procure cooling elements

7.      Size top and bottom headers

8.      Assemble heat pipes with cooling elements and with headers

9.      Conduct trial operation

10.  Assemble with the engine and test for long  term monitoring and evaluation for reliability

It is expected that the development work should take about 30 months time.

PROJECT COST:  The equipment and materials costs along with the cost of consultancy and engineering hours are estimated at present market rates based on preliminary data obtained through pre-tendering and consultation. The likely costs are,

1.      Heat pipes: 2.50 lakhs

2.      TIG welding or Plasma welding : 4.00 lakhs

3.      Ultra High Vacuum system : 2.50 lakhs

4.      Cooling plates: 0.50 lakhs

5.      Miscellaneous items and materials: 1.50 lakhs

6.      Assembly, installation and commissioning: 1.00 lakhs

7.      Operation and maintenance: 1. 00 lakhs

8.      Service and consultancy: 1.00 lakhs

9.      Cost of engineering hours: 3.00 lakhs

Total likely cost of the project is 17.00 lakhs. 

Heat Pipe Generator Cooler

Project Title

Design & Development of 220 KW Heat Pipe Generator Cooler 

(B YH 01 265 RD 48)

Objective  

To develop a loop type heat pipe module and demonstrate as generator cooler

Project Description

For the first time, a loop type heat pipe is being developed with copper/ethanol and stainless steel/ethanol heat pipes. These special heat pipes have several features favorable as a generator cooler. The evaporator sections on which the hot air from the generator flows are separated from the condenser sections over which the cooling water is circulated whereby water leakage into the system is effectively eliminated. Manufacture of evaporator and condenser sections made from high fin and low fin tubes respectively can be carried out separately and integrated subsequently. Each stage comprises a row of heat pipe sections TIG welded to common headers. Each stage heat duty will be larger than a row of equal number of individual heat pipes reducing the overall module size. The evaporator section of each loop is made of 20 Nos. of high fin bimetallic tubes made of 2m long 18 mm id copper core tube and 45 mm od aluminum fin tube with a fin height of 11 mm. The fin density is 390 fins/m. The tubes are TIG welded to a common top and bottom headers 50 mm and 33 mm diameter respectively. The

Loop Type Heat Pipe Generator Cooler

condenser consists of 20 Nos. of integral low fin copper tubes 18 mm id similarly welded to common headers.

     The two sections are integrated with connecting pipes to form a closed loop. Two 12 mm valves are provided, one to serve evacuation and filling and the other as a drain valve. The valves are dispensed with once the right proportion of fill charge is determined by repeated trials on the first loop. The unit will be a completely sealed system.

      Manufacture of the first loop was completed. Evacuation and filling was in progress.

Heat Pipe TWT Cooling System

Project Title

Design & Development of Heat Pipe TWT Cooling Systems

(CL 9 95 066 RD 48)

Objective

To design, develop and supply 5 nos. of heat pipe TWT cooling system for an application involving strategic electronic thermal management.

Project Description

Under a prestigious commercial project valued at about Rs30.0 lakhs, 5 Nos. of heat pipe cooling systems for Travelling Wave Tubes (TWT) with power dissipation up to 2000 W used in communication systems were developed.  Variable length copper /ethanol heat pipes of 18 mm diameter and lengths ranging from 350 to 450 mm bent appropriately to form a plate-fin condenser forced cooled by an ID fan delivering maximum flow rate of 150 lts/s. The fan is directly mounted on the condenser duct. The system was integrated with the respective TWT and the operating temperature was maintained at a mandatory level of 100 ⁰C. The system is of rugged construction made to stringent specifications. The measured overall thermal resistance of the cooling system was 0.025 W/K under actual

Heat Pipe TWT Cooling System

operating conditions. The units were supplied after successful operation and environmental testing of the systems. This development work with heat pipes was the first of its kind in India.

See a butterfly shaped CPU Cooler with Heat Pipes from zerotherm.net  shown in quietpc.com.

Heat Pipe Steam Condenser

Heat Pipe Steam Condenser

Project Title

Design & Development of a 300 kg/hr Heat Pipe Steam Condenser

(B YH 92 013 RD 48)

Objective

To gain experience in the indigenous manufacture of heat pipes and heat pipe steam condenser operation

Project Description

A prototype 300 kg/hr heat pipe steam condenser was indigenously developed and successfully tested at BHEL/R&D steam generator facility. The 1.5 m long 25.4 mm diameter integral high-fin aluminum tubes were used to manufacture the heat pipes. The fin height is 11 mm and the fin density is 350 fins/m.  Acetone is the working fluid. A four layer #100 and #200 composite stainless steel wire screen served as a wick. The unit was fabricated with 150 Nos. of heat pipes laid in a staggered arrangement. The airside heat transfer area for the unit is 150 m². Each heat pipe is capable of handling 1000 W. The unfinned evaporator sections of the heat pipe, 0.5m long, were located in a rectangular steam plenum, which was continuously evacuated by water-ring vacuum pump. The finned condenser sections 1 m long inclined to the vertical by 15⁰ are exposed to a blast of cold air circulated by an ID fan mounted on the top of the unit.

  

Evacuation and Filling of Heat Pipe Steam Condenser in Progress  

    The equipment was instrumented for measuring the vacuum level in the steam plenum, the steam temperature and condensate flow rate. The steam temperature was maintained at about 60 ⁰C. The steam plenum is connected to the 600 kg/hr oil fired steam generator available at BHEL/R&D. A glass level-indicator is fitted to the plenum to monitor the condensate level. The indicator also helped to ensure that the heat pipe evaporator ends are not flooded with the condensate thereby reducing the effective evaporator length.

Heat Pipe Condenser under Testing

  The prototype heat pipe condenser was continuously operated and a condensate rate of 300 kg/hr was measured. With the successful testing of a laboratory scale steam-condensing unit using heat pipes, several significant applications for dry condensing systems can be foreseen. While the main thrust area is the clean coal technology with dry type large steam condensers using carbon steel/ammonia heat pipes for economical production and operation in water scarce zones, the product will find application in many process industries.

Heat Pipe Air Preheater

Project Title

Design, Development & Demonstration of a 1.0 MW Heat Pipe Air Preheater

(B YH 88 977 RD 48)

Objective                           

To gain hands-on experience on the operation of a heat pipe air preheater

Project Description

A 1.0 MW heat pipe air preheater was developed and successfully tested on the oil-fired test facility at BHEL/Ranipet. The design of the air heater as a counter flow heat exchanger is based on 4 m long, 37 mm diameter internally grooved, integrally finned low-carbon steel heat pipes. Water is the working fluid. The heat pipe has an extra-unfinned length of 5% on the condenser side to accommodate the noncondensible gases produced during operation. BHEL/R&D evolved the designs while the manufacturing drawings as per standards were prepared by BHEL/Ranipet to suit the test track at Ranipet. The heat pipes were procured from M/s Fujikura, Japan as per our design and the manufacturing and assembly of the air preheater was carried out at BHEL/R&D. The unit uses 200 nos. of the heat pipes and is of overall size 4200 x 1700 x 650 mm. The equipment was laid at 7⁰ inclination to the horizontal and integrated with the test track with upstream/downstream ducts for flow stabilization.

The Heat Pipe Air Preheater
       

     Adequate instrumentation for the measurement of flow rate and temperatures is provided. Four calibrated venturi meters on gas/air side measured the flow rate while a peizoring arrangement measured the gas/air side pressure drop. The gas/air temperature is measured with 15 nos. of 28 SWG chromel-alumel thermocouples fitted in the stream. The heat pipe metal temperature on the evaporator side is also measured with a chromel-alumel thermocouple. The measured variables are:1) the gas/air flow rates, 2) the inlet/outlet gas/air temperatures, 3) the gas/air side pressure drop and 4) heat pipe metal temperature.

    The hot gases were generated for the experiments by an oil-fired combustion chamber located in the open circuit test track. The combustion nozzle has a small blower attached for mixing and distributing the gases. The hot gas flows over the evaporator sections of the heat pipes while the condenser sections receive a blast of cold air before entering the combustion chamber.

Heat Pipe Air Preheater under Integration with Test Track  

The air preheater was successfully tested at a heat pipe operating temperature of less than 200 ⁰C. The duty handled by the unit was 0.88 MW at an air flow rate of 17 kg/sec. The prototype testing under the project provided BHEL/Ranipet engineers an opportunity to gain adequate experience in the operation of heat pipe air preheaters.