Transactions of the Korean Nuclear Society Spring Meeting Pyeongchang, Korea, May 27-28, 2010

The Design of the Annular Linear Induction EM Pump with a Sodium Flowrate of 35 kg/sec

Hee Reyoung Kim, Tae Ho Lee and Yong Bum Lee Korea Atomic Energy Research Institute, Dugjindong 150 yuseong Daejeon, [email protected]

1. Introduction from the characteristic analyses on the developing force according to various variables by using the equivalent Generally, an electromagnetic (EM) pump has been circuit method [1-3]. Fig.2 shows equivalent circuit on one phase of the EM pump. employed to circulate liquid metal with a high electrical conductivity by the electromagnetic force () which is the cross product of the and its perpendicular current. Therefore, an EM pump has its advantages over a mechanical pump such as no noise, no rotating parts, and its simplicity. Actually, it can be used for the Sodium Fast Reactor (SFR) which uses liquid sodium with a high electrical conductivity as Fig. 2. The equivalent circuit for an EM pump design a coolant. In the present study, the annular linear (V : Input I : Input current induction EM pump with a flowrate of 2,265 L/min and R1 : Primary resistance X1 : Primary reactance a head of 4 bar is designed by using an electrical Xm: Magnetizing reactance I’ : Secondary current equivalent circuit method which is applied to linear R2 : Secondary resistance s : Slip) induction machines. The designed pump will be used for the verification of the elements, which are IHX, It consists of two parts. The primary part is the AHX and DHX, in the component performance test electromagnet with cores and coils. The secondary one sodium loop for the sodium thermo-hydraulic is the moving liquid sodium fluid inside the duct experimental facility. The pump is manufactured and channel. From the balance equation on the developed fabricated to meet the requirements of the material and power, the relationship between developing force and a functioning in high temperature-sodium environments. flowrate is obtained as follows; The P-Q characteristic is theoretically calculated on the 3I 2 R 2 (1 − s) ΔP = 2 designed pump according to the input currents and Q 2 2 2 (R2 / X m s +1) voltage. where ΔP is developing pressure and Q is the flowrate. 2. Method and Results Each equivalent resistance and reactance is given by Laithwaite’s standard design formula. 2.1 The design analysis of an EM Pump 2 2 2 2 πρcqk m D N p 0 , 2πμ0ωD0λc N R1 = 2 X1 ≅ k f kd pτ pq 6μ ωτπD (k N)2 2 0 0 w , 6πDρr '(kw N) X m = 2 R2 = π pg e τp

Using the above resistances and reactqances, the developing force is reduced to functions of pump variables; Fig. 1. Cross-sectional view of the annular linear induction 2 2 EM pump 36σsfτ (μ0kwNI) ΔP = 2 2 2 2 pge {π + (2μ0σsfτ ) } The cross-section of the annular linear induction EM pump to be designed is represented in Fig. 1. It is The developing force can be calculated at various largely divided into two parts. One is the electromagnet values of the pump’s geometrical and operational made up of the inner and outer cores with a high variables. The length and diameter of the EM pump magnetic permeability and exciting conductor coils. have the fixed values due to the loop structure. The other is a duct with a narrow annular channel gap Therefore, the design variables are optimized according for the sodium flow [1]. Firstly, the pump has the to the change of the other variables such as gap, pole geometrical variables of the inter-core gap, diameters of pitch, coil turns except the length and diameter. On the the inner core, core length. Also, it has the other hand, the hydraulic head loss at the narrow electromagnetical variables of the input current, voltage, annular flow gap is given by Darcy-Weisbach [4]; frequency, coil turns, the number of pole pairs and pole ρηLv2 pitch. Therefore, the design variables are determined ΔP = L 2g Transactions of the Korean Nuclear Society Spring Meeting Pyeongchang, Korea, May 27-28, 2010

2.2 The Designed Specification of the EM Pump consideration of the operational environment such as a

high temperature of 550 ℃, chemically reactive sodium The main design values for the EM pump are represented in Table 1. fluid, magnetic field distortion, etc. Fig. 2 shows the completed three-phase annular linear induction Table 1. The characteristic of the EM pump electromagnetic pump for the liquid sodium circulation Design Design Variables in the loop. Values Flowrate Q [l/min] 2,265 Hydro Developing Force ΔP [bar] 4.07 dynamical Temperature [oC] 550 Velocity [m/sec] 6.5 Slip s [%] 49.8 Head loss [bar] 0.16 Pump Length L [m] 1.3

Pump Diameter D [m] 0.46 Geometrical Inter-core Gap g [m] 0.02 Flow gap [m] 0.016 (a) The front view (b) The side view

Input Current I [A] 125 Fig. 2. The completed annular linear induction EM pump Input Voltage V [V] 426 Electro- Input VA VI [VA] 92.2 3. Conclusion magnetical Turns/Slot N [#] 32 Frequency f [Hz] 60 The annular linear induction electromagnetic pump Number of Pole Pairs p [#] 6 was designed and manufactured by the Pole Pitch [m] 0.11 electromagnetic and hydraulic calculation. In the near Goodness factor 0.9 future, the experiments will be carried out with an experimental uncertainty analysis for the pump The length and diameter of the pump are 1.3 m and thermo-hydraulic performance. 0.46 m, respectively, due to its loop geometry. The inter-core gap is 0.02 m by consideration of the Nomenclature diameter and thickness of the commercially-produced pipe. Accordingly, the flow gap is 0.016 m. For the D = mean diameter of the fluid high goodness factor and P-Q characteristic, the pole D0 = diameter of the inner core pitch (or number of pole pairs) is 0.11m (or 6). The g = inter−core gap three phase and voltage are applied ge = effective inter−core gap(= Kcⅹg) to the pump and the input frequency is 60 Hz of the Kc = Carter’s coefficient commercial frequency. The head loss in the flow gap is kd = t/w (t : slot depth) 0.16 bar by calculation at the nominal operation point. kf = slot−filling factor (0.5−0.6) It is negligible compared with the nominal developing kp = tc/w (tc : slot pitch, w : slot width) k = winding coefficient pressure of 4 bar. w m = number of input phases P-Q curves at designed values are shown in Fig. 3. In N = number of turns of coils per slot Fig. 3, the pumping flowrate reaches the synchronized p = number of pole pairs one when it is over 4,000 L/min much more than the q = number of slots per pole per phase nominal one of 2,265 L/min. λ =1/12 ⅹk (1 + 3α), α = chording factor c d ρc = resistivity of the coil conductor 10 ρr = surface resistivity of the fluid τ = pole pitch 8 μ = magnetic permeability of vacuum I=150 A, V=511V 0 ω = 2πf (f : input frequency) 6 I=125 A, V=426V 4 Operating point REFERENCES I=100 A, V=341V 2 [1] Hee Reyoung Kim et al, “P-Q Characteristic of the Developing Pressure(Developing bar) Electromagnetic Pump with the Flowrate of 60 l/min”, Korean 0 Nuclear Society, Spring Meeting, Jeju, Korea, May 26-27, 0 1000 2000 3000 4000 5000 2005. Flowrates(L/min) [2] A. Oto, "Sodium-Immersed Self-Cooled Electromagnetic Pump Design and Development of a Large Scale Coil for Fig. 3. P-Q characteristic of the designed EM pump by the High Temperature", Nucl. Tech. 110, 159, 1995. theoretical calculation [3] S. A. Nasar, Linear Motion Electric Machines, John Wiley&Sons, Inc., New York, 1976. According to the designed specifications, the pump [4] White, Fluid Mechanics, John Wiley&Sons, Inc., New was actually manufactured and fabricated by a York, 1988.