Gas Technology Institute UTSR Fellow: Miad Karimi. > Summer 2017

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1 Gas Technology Institute UTSR Fellow: Miad Karimi > Summer 2017

2 About the Fellow Graduated from Georgia Institute of Technology with BS in Aerospace Engineering, May 2014 Enrolled in 3 rd year of PhD in Aerospace Engineering at Georgia Institute of Technology Areas of interest: Combustion kinetics, aerodynamics and optical diagnostics in reacting flows Current research project: Shock-driven autoignition delay of oxy-combustion 2

3 Project Low Reynolds number heat transfer coefficient experiment Tasks overview: Experimental setup schematic Preliminary heat exchanger sizing calculations Development of the experimental facility Preliminary exhaust duct sizing of the test article 3

4 ~600 C Vent Experimental setup schematic Rotameter Differential pressure sensors ΔP Manual ball valve T T T T T Air Compressed air (room temperature) Rotameter ~600 C Vent Heat exchanger 1 (target outlet temperature C) P ΔP T T T T T T T T T T T T T T Test article T ~500 C Vent Thermocouples Heat exchanger 2 (target outlet temperature C) 4

5 Required length (in) Preliminary heat exchanger sizing calculations (I) Q = Heat exchanger 1 sizing: T1=300 K T2=1500K 0.680kg Q = mc p T KJ kgk 1200K = 0.3KW Required surface area U( W/m 2 K) A(m 2 ) A(in 2 ) The required area needs to be validated experimentally and the heat exchanger for this test should be capable of having at most 82.2 in 2 surface area. ½ diameter tube is recommended considering the overall length of the heat exchanger assigned to the project. Q = AU T m 40 T m = T ln T = K /4" tube 1/2" tube Overall Heat transfer coefficients (W/m 2 K) 5

6 Required length (in) Preliminary heat exchanger sizing calculations (II) Q = m = Q = Heat exchanger 2 sizing: 0.680kg KJ KgK KJ 0.840kg T m = T1=300 K T2=700K Q = mc p T KJ kgk 200 K KJ 700K = = Kg m total = 0.840Kg/ KJ kgk Q = AU T m T ln T for one side 400K = 0.1KW = K Required surface area U( W/m 2 K) A(m 2 ) A(in 2 ) Overall Heat transfer coefficients (W/m 2 K) The required area needs to be validated experimentally and the heat exchanger for this test should be capable of having at most 65.1 in 2 surface area. However, due to the length of the heat exchanger assigned to the project the validation can only be done for maximum of 32.7 in 2. ½ diameter tube is recommended due to length limitations. 1/4" tube 1/2" tube 6

7 Development of the experimental facility Heat exchanger 1 Mounting panel Heat exchanger 2 Manual ball valve Compressed air Hot flow out To the test article Outflow to heat exchangers Cold flow in Rotameters Thermal insulator fabricated 7

8 Preliminary exhaust duct sizing of the test article Air pre-heat duct is by itself a counter flow heat exchanger For a given amount of heat available for preheating cold intake air, due to size restrictions of the test article, the amount of surface area available in the duct is limited One possible solution is to add cylindrical pins along the duct The size and number of pins required need to be calculated Air pre-heat duct (contains heat rejection fins) Cold air intake Hot air intake 8

9 Preliminary exhaust duct sizing of the test article Test conditions: T 1 = 163.9K T 2 = 269.9K Average Reynolds number: T in = K ρ 1 = 1.204kg m 3 T out = K ρ 2 = 0.57kg m 3 ρ avg = 0.887k gτm 3 T m = T 2 T 1 ln( T 2 T 1 ) = = 212K V = mሶ ρ avg A = k gτs ec 0.887k gτm 3 )( m 2 = m Τ s ec wetted diameter (D m ) = m Re = VD m θ avg = 0.663m sec )(0.0028m m 2 Τs ec =

10 Preliminary exhaust duct sizing of the test article Overall heat transfer coefficient: 1 U = 1 h 1 + L k + 1 h 2 A required = Pin design: Q U T m = 0.023m 2 = 35.65in 2 h 1, h 2 : Heat transfer coefficients k: Thermal conductivity L: Inside duct length h 1 = h 2 = Nu k D Nu k D W = m 2 K W = m 2 K U = W m 2 K Initial design surface area without pins 19.5in 2, therefore in 2 additional surface area needs to be implemented into the new design. Including 30% of calculations margin the number of cylindrical pins required is 200 with diameter of 0.25 and of height. 10

11 Conclusion Preliminary heat exchanger sizing calculations completed Experimental facility assembly started and currently under development Preliminary exhaust duct sizing calculation completed At this stage of the project no test data to be shared 11