Development of a 1kW exhaust waste heat thermoelectric generator.
Although the technology of combustion engines is reasonably well developed, the degree of efficiency is considerably low. Considerable amount of the energy of around 35% is lost as exhaust waste heat, and up to 30% is dissipated in the cooling circuits. Due to this, thermal recuperation has a great potential for raising the efficiency of combustion engines. In order to meet the ever-increasing consumer demand for higher fuel economy, and to conform to more stringent governmental regulations, auto manufacturers have increasingly looked at thermoelectric materials as a potential method to recover some of that waste heat and improve the overall efficiency of their vehicle feets. Seeking new possibilities to make vehicles greener and more efficient, the industry wants to use the waste heat which passes through the exhaust system almost completely unused in the past. The combination of heat exchanger and thermoelectric material integrated into the vehicle environment results in high demands on design, size & dimensioning of the thermoelectric generator system. As a company specializing in the manufacture of exhaust systems for the automotive industry, Eberspacher Exhaust Systems of Americas is uniquely well-positioned to develop and integrate an in-line system for the capture and conversion of thermal energy into electrical energy, and to account for the effects of the heat exchanger on the rest of the exhaust system and engine. In this paper, the stages of the thermal and mechanical design of heat exchanger, material selection, analytical simulations of thermal, contact phenomena, finite element methodology used, physical TEG prototype fabrication and testing stages involved in the development of a 1000 Watt thermoelectric generator (TEG) for a diesel engine of a military tank are explained in detail.
CITATION: Meda, L., Romzek, M., Zhang, Y., and Cleary, M., "Development of a 1kW Exhaust Waste Heat Thermoelectric Generator," SAE Int. J. Commer. Veh. 9(1):2016, doi:10.4271/2016-01-1273.
Thermoelectric generators (TEG) are solid-state devices that convert heat directly into electrical energy using a phenomenon called the Seebeck effect. The TE materials used in thermoelectric generators are semiconductors with low thermal conductivity and high electrical conductivity. There are no moving or rotating parts in this device. To generate electrical energy, waste heat is applied to the junction of two electrically opposed materials that are cooled at the opposite end. A TE module consists of multiple leg pairs, each made of n-type and ptype TE materials, which are connected electrically in series and thermally in parallel to form a TE module. The modules are then incorporated into a heat exchange assembly with a hot and cold side forming a thermoelectric generator (TEG). A typical TEG unit consists of a heat exchanger core, thermoelectric modules, a coolant heat exchanger, exhaust gas inlet and outlet diffusers, a bypass pipe (which routes exhaust gas away from the heat exchanger when necessary) and a bypass valve to regulate the flow though the heat exchanger
First, a conceptual TEG system architecture and assembly consisting of TEG modules, hot side heat exchanger, cold side heat exchanger, gas and coolant inlet and outlets is envisioned. The TEG system includes a series of thermoelectric modules (TEMs) sandwiched between the exhaust heat exchangers and cold heat exchangers that effectively transfer the heat into and out of the TEMs in order to establish the maximum temperature gradient. Next, development of 1-D heat & mass transfer analytical tool for a TEG system consisting of hot and cold side heat exchangers and TEG modules is explained. The tool is then used to optimize the fins in the heat exchangers. Finite element method is also used to evaluate the contact pressure distribution adjacent to TEM under bolted assembly loading and under the operating hot conditions. Computational fluid dynamics is also used to optimize the inlet regions of heat exchangers. Once the final optimized fin selection and heat exchanger assembly aspects are decided based on 1-D and FEA simulation results, initially a modular 200 W system representing 1/5th of a complete 1000 W TEG system is fabricated and tested. After the successful testing of a 200 W TEG system, a final 1kW system is also fabricated and tested. The steps carried out in the above process are described in the following sections.
HEAT EXCHANGER DESIGN
The heat exchanger design utilizes a rectangular, slab like heat exchanger core. Generally, if the exhaust stream is split into two or more streams within the heat exchanger, a greater surface area for the attachment of thermoelectric modules can be created Extracting thermal energy from the exhaust gas is difficult because of the low gas heat transfer coefficient, typically around 100W/m2-K, at the design condition. The extraction of thermal energy in a heat exchanger can be enhanced by the inclusion of fins in the gas stream, Fins may be plain, offset, triangular or louvered. Fins enhance the overall rate of heat extraction by increasing the heat transfer coefficient and by increasing the overall conducting surface area in contact with the exhaust gas. However, this increase in thermal extraction is bought at the cost of an increased pressure drop across the fins. Within the exhaust, the pressure drop across the TEG unit must be kept within limits; otherwise the overall performance of the engine will be degraded. The literature contains a number of empirical relationships for evaluating the increased heat transfer coefficient and the resulting pressure drop associated with a given fin design. Plain rectangular fins have been chosen for evaluation for inclusion in the TEG in this study as they represent a reasonable compromise between enhanced heat transfer and pressure loss, in addition the small number of design variables and relative ease of manufacture makes them an attractive design choice.
To maximize electrical power output, the design of the TEG was made to get the highest heat transfer between hot gas and the thermoelectric modules, while at the same time keeping exhaust line back-pressure at an acceptable level. Once evaluated for a given fin design, the overall thermal performance of the heat exchanger was calculated using the [epsilon]-NTU (efficiency, number of transfer units) method. With this method, an overall heat transfer coefficient is derived. This overall value has contributions from the exhaust gas, including the contribution to the increased conduction area from the fins, a contribution from the solid material including TEG modules, graphite layers adjacent to TEG modules between the hot and cold fluids, and the contribution from the coolant heat transfer coefficient. In a conventional heat exchanger, the thermal resistance from the metal interface between the primary and secondary fluids is usually small. With a TEG unit, however, a thermoelectric material is interposed between the hot and the cold surfaces. The thermal conductivity of these materials is very low, typically 1.2 to 3 W/m-K. This is similar to the thermal conductivity of glass or brick and makes a considerable impact on the heat transfer capabilities of the TEG unit.
Consequently, the effect of the additional thermal resistance due to the thermoelectric materials needs to be considered from an early stage in the design. The overall heat transfer of the TEG unit was evaluated for thermoelectric module thicknesses of 5 mm. Some generic Exhaust Heat Exchanger Requirements are 1) Maintain a uniform temperature differential to the TE material at the optimum working TE range, 2) Maximize the overall heat flux through the TE material within the working range, 3) Minimize the exhaust gas-side pressure drop, 4) Minimize system weight and the incremental thermal inertia of the device, and 5) Providing a means of controlling the heat flux to the TE material and regulating the pressure drop.
Figure 1 shows an image of a TEG Module. The TEG modules in this research are made of nanostructured bulk half-Heusler uncouples. Since half-Heusler materials are oxygen-sensitive, the raw module consisting of 28 n- and p- unicouples is sealed in a stainless-steel enclosure in vacuum with two electric feed-throughs. A thin graphite foil is employed between the hot side of the raw module and the enclosure cover to provide a flexible thermal contact in order to relieve thermal stresses under device operation, and the cold side of the module is soldered to the bottom of the enclosure. Refer  for more information on the module.
ANALYTICAL THERMAL MODEL FOR THERMOELECTRIC GENERATOR
Heat Exchanger Models
The performance of a heat exchanger can be determined by examining the heat loss and heat gain that takes place between its working fluids.
The actual heat transfer rate can be determined from
q = [C.sub.c]([T.sub.c,out] - [T.sub.c,in])
q = [C.sub.h]([T.sub.h,in] - [T.sub.h,out])
[C.sub.c] = [m.sub.c]*[C.sub.P*c]
[C.sub.h] = [m.sub.h]*[C.sub.p*h]
The smaller one is defined as Cmin and the larger Cmax
[q.sub.max] = [C.sub.min] ([T.sub.h,in] - [T.sub.c,in])
Where [C.sub.min] is the smaller of [C.sub.h] and [C.sub.c] and [DELTA][T.sub.max] = [T.sub.h,in] - [T.sub.c,in]
q = [epsilon][q.sub.max]
q = [epsilon][C.sub.min] ([T.sub.h,in] - [T.sub.c,in])
Where Cmin is the smaller of Ch and Cc and the effectiveness of heat exchanger can be written as
[epsilon] = [q]/[q.sub.max] = [actual heat transfer rate]/[maximum possible heat tranfer rate]
To determine the effectiveness, [epsilon] we involve a dimensionless quantity called number of transfer units which is expressed as NTU=UA/Cmin, where U = overall heat transfer coefficient. The effectiveness of the cross flow heat exchanger is given by
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]
Where C* = Cmin/Cmax
The flow of heat from the hot air to the cold coolant can be represented by Newton's Law of cooling.
Q=UA(Th-Tc), UA is the reciprocal of resistance.
Nu = 0.023 R[e.sup.0.8] P[r.sup.n]
Here, n = 0.4 if the fluid is being heated, that is, if the wall is at a higher temperature than the entering fluid, and n = 0.3 if the fluid is being cooled.
Where Prandtl number is Pr = (Cp. [micro]) / [K.sub.fl] and Nu and heat transfer coefficient are related by h = [N.sub.u.] [K.sub.fl] / [D.sub.h]
[K.sub.fl]: Fluid thermal conductivity
[c.sub.p]: Fluid specific heat at constant pressure
[micro]: Fluid viscosity
EQUIVALENT THERMAL RESISTANCE MODEL FOR TEG
The TEG system includes a series of thermoelectric modules (TEMs) sandwiched between the exhaust heat exchangers and liquid cold heat exchanger that effectively transfer the heat into and out of the TEMs in order to establish the maximum temperature gradient. TEM's consisting of semiconductor thermoelectric materials are relatively less compliant. The thermal stress between a TEM and the wall of the HEX affects both heat transfer as well as the durability. To reduce the thermal stress in the TEM, compliant pads are used at the interface, although the pads act as a barrier against thermal conduction. Graphite pads are used as compliant pads in this research . Heat transfer from the hot side HEX will occur in the fin through different types of resistances which includes convection and conduction, as presented in Figures 2 & 3. After defining the equations for each resistance, a thermal circuit is built, and an equivalent thermal resistance is calculated. The resistance expressions for hot-side heat exchanger are given below. The other resistances can be obtained similarly from the model presented in Figure 3.
R1 = 2/(h.[N.sub.f].S.L)
R3 = t/([K.sub.f].[N.sub.f].S.L)
R4 = [t.sub.p]/(2Kp [N.sub.f].S.L)
The efficiency of the fin is given by
[[epsilon].sub.f] = tanh(mLc) /mLc; m=Sqrt(h*P/ [K.sub.f] *Ac); Lc = P/2
Pr. Drop through HEX fins core = (4*f*L*p*v2) /(2*[D.sub.h])
Where, f is fanning friction factor.
Parametric Fin Design Analysis
Analytical 1-D code, developed in the above section was employed to calculate the fluid flow and heat transfer in order to optimize the heat exchanger design and obtain the maximum heat transfer rate with the minimum pressure drop. The heat exchanger involves an array of fins in order to increase the surface area and the heat transfer rate. Considering the trade-off between manufacturability and the performance, the plain (simple rectangular) fin is selected for the heat exchangers, and the nickel alloy is used as the fin material due to the relatively high thermal conductivity, high service temperature, and corrosion resistance that meet all the requirements of this research. The key heat exchanger design parameters including the fin thickness and fin packing fraction were optimized using analytical tool developed here. For the analysis purpose, a single layer of hot HEX with 40 modules each above and below the hot side HEX, and 2 layers of cold HEX are considered. This is a modular 200 W model representing 1/5th of the full size model. The exhaust flow rate of 90 g/sec & 550 C as temperature at the inlet was used for the 200 W TEG model since the total exhaust mass flow rate is 450 g/s and average exhaust temperature is 550 C near the inlet for the diesel engine employed in this research. For the cold side HEX, water flow conditions are 15 Liters/min (10 C to 90 C).
The analytical 1-D calculation using the above inlet conditions was used to calculate he temperature differences [DELTA]T across the TEMs, the heat flow through the TEMs and the pressure drop across the heat exchanger. A Complete 200 W system consisting of 80 modules is considered in the analysis although most of the results (average) are reported only for one module (Figure 4 (a)). The Figures 4 (b), (c) & (d) show variation of TEM average [DELTA]T, Heat flow from TEM/module and back-pressure with the hot HEX fin package fraction respectively. It can be seen from Figure. 4 (b) and (c) that, both the TEM [DELTA]T and the heat flow increase with fin packing fraction, and then gradually plateaus with the increase of fin packing fraction. However, the pressure drop increases exponentially as fin packing fraction increases due to increase in the exhaust flow speed. The final fin design selection is based on a compromise between maximum [DELTA]T TEM and back pressure limits and also considering the manufacturability. The analytical results presented here are similar to CFD results published earlier .
In addition to above type of analytical studies, quite a few different heat transfer performance studies were carried out using the 1-D analytical tool and the results obtained are graphically displayed as shown in Figure 5. The graph (four dots) shows the T TEM of all four TEMs along the downstream of the exhaust flow. The baseline design has Nickel fins and it can be seen from Figure 5 (designs 1 to 3), the analysis predicts considerably high thermal performance as the cold water temperature is decreased from 90 C to 10 C. It can also be seen from the same graph how the TEG performance deteriorates if the fins were made of stainless steel (Design 7) relative to Nickel fins (design 1). It can be seen from the same graph (designs 5 & 6), a slight increase in performance of baseline (design 3) can be obtained either by having 25% more fins (design 5) or by increasing the base fin thickness by 50% (design 6) and also can be inferred that both designs 5 & 6 have roughly equivalent performance.
TEG ASSEMBLY SETUP, CONTACT MECHANICS FEA & TESTING
Before building the 1kW or even the 200 W system assembly, the concept of assembly process was simulated using finite element method. It was decided to use four bolts at the corner of each TEG module. The four bolt loads selected are such that they apply a load equivalent of about 0.6 MPa on the module. In order to simulate this, first a FEM model consisting of TEG module including module internals is built. The LHS of Figure 7 shows the pressure distribution on the stainless steel cover hot and cold sides of a TEG module under the initial bolt loads. The initial contact pressures on both hot and cold sides of TEM are less than 0.75 MPa under this load. Next step is to heat the system and calculate the pressures. The temperature distribution used under heat is shown in Figure 8. Figure 7 also shows the how contact pressure changes under heat on both the hot and cold sides of the modules. FEA predicts loss of pressure in the middle of the cold side and somewhat of high contact pressures at the corners. But, the value of corner pressure values of 1.62 MPa are mostly on the outer steel jacket of the TEM module and was deemed acceptable. Figure 9 shows gap distribution on the cold side of a TEG module under heat & bolt loads. It can be seen from Figure 9 that maximum gap between the TEM and graphite pad adjacent to cold side HEX occurs not in the middle, but somewhat on the sides of the module which is relatively better. Figure 9 also depicts slight bowing of the TEM under hot conditions due to relatively high lateral expansion on the hot side of TEM. This bowing under hot conditions obviously results in concentrated pressures of 1.38 MPa in the middle of hot side TEM, increasing from an initial pressure of 0.69 MPa. These values are deemed acceptable based on the strength of TEG modules and hence proceeded to build a 200 W physical prototype model.
There were several different suggestions from several groups regarding type of pads to use adjacent to TEMs. For example GAP PAD  was suggested although our past experience had shown that graphite pad was a good candidate. Hence a test was designed where pads were placed adjacent to TEM bottom & top faces and bolted using 4 corner bolts and a load cell was inserted to measure the load (Figure 11) and a fixed bolt torque was applied on each of four bolts. After few minutes of loading, the graphite and GAPPADs were removed from the setup and were visually inspected. Figure 10 shows the condition of GAPPAD and graphite after loading and unloading. It can be seen that GAPPADs expands outwards under increasing bolt loads leaking past the initial boundaries. It can also be seen from Figure that Graphite pads showed greater resistance to compression. Further, pressure film contact pressure distribution shows better and good contact behavior with graphite pads.
Figure 11 shows the graphical display of the load retained in the bolts after 12 hours loading using GAPPAD & graphite pads as interface materials. It can be seen from Figure 11 that GAPPAD load retention capability has reduced from an initial 124 lbs to 82 lbs on the hot side and from 55 lbs to 36 lbs on the cold side in 12 hours. There was not much change in the load carrying capacity of graphite pads after 12 hours of loading and unloading. Hence graphite was selected as an interface material. Similarly a study of spring and Bellville bolt washers using graphite pads was made. Figure 12 shows the reliability of washers under different bolt torque loading and pressure loads. It can be seen from Figure 12 that spring washers give inconsistent loads each time bolt is loaded at a particular torque value, whereas Bellville washers behave more consistent load carrying capacity every time the bolts are loaded to a particular torque.
The cold side HEX inlet region was optimized using CFD for uniform flow through channels between the fins as can be seen from Figure 13. Similarly inlet cones of hot side TEG system for both 200 W and 1000 W systems were optimized to have uniform flow through hot side HEX inlet conduits.
PROTOTYPE FABRICATION, EXPERIMENTAL SETUP AND TESTING
200 W System
In order to validate the 1-D analytical predictions, a 200 Watt design with proper fin packaging on the hot side HEX and on the cold side HEX was fabricated and tested. The heat exchanger was fabricated using 0.2 mm thick nickel fins of 15.5% packing fraction to provide an optimal balance between heat flow rate, pressure drop and manufacturability. The TEM cold-side surfaces were cooled using aluminum cold side HEX with coolant flow in perpendicular direction to the exhaust flow. The TEG was assembled with 0.6 MPa clamping pressure using 62 uniformly distributed pressure pins, and 0.5-mm-thick graphite pads were inserted between all the interfaces between the hot side HEX, TEMs and cold side HEX. The TEG was instrumented with thermocouples and flow meters to measure the temperatures and the exhaust and coolant flow rate at various locations of interests. The test setup is shown in Figure 14. The figure also shows the module performance under various T TEM. Table 1 shows the table of performance comparison between the measured test results and 1-D analytical tool predictions. It can be seen from this table that as predicted by 1-D tool, the temperatures of outlet gas and water matched the measurement results fairly well under different water inlet temperatures of 10 C & 86 C. It can also be seen from this table that when the water temperature is increased from 10 C to 86 C, there is a drop of about 50 C in T TEM resulting in corresponding drop in measured power from 270 W to about 228 W (Figure 5 - Designs 1 & 3).
1000 W System
Due to modular nature of the 200 W system and due to the success of the measured power, the 1000 W system was fabricated in the same manner by stacking up the modules and heat exchangers in layers one above the other and fitting the bolted unit by a big inlet and outlet cones which were optimized (CFD) to have a lower back pressure. As shown in Figure 15, the complete 1000 W TEG in this work includes 5 layers of exhaust heat exchangers, 10 layers of TEMs with 40 modules on each layer, and 6 layers of cold HEX. Each heat exchanger layer contains 10 identical units with almost equivalent exhaust mass flow rate. The system is then tested by connecting to a 13 L, inline 6 cylinder 450 HP Diesel engine. The tested conditions at the inlet; flow rate of 458 g/sec, 553 C gas temperature, and water temperature of 42 C. The 1-D analytical tool results and measured results are shown Table 2 and they matched reasonably well. Under the above conditions, the TEG system produced 1003 W.
A 1000 Watt thermoelectric generator (TEG) for a diesel engine of a military tank (TARDEC) is designed, built and tested. The stages in the thermal and mechanical design, material selection and testing process are outlined. The process involved coming up with the TEG's system design based on the space given and on the TEG's performance calculations. In order to optimize the heat transfer and flow, an analytical 1-D heat and mass transfer code specifically for thermoelectrics is developed. The analytical calculations involved evaluation of heat transfer, back-pressure and temperature difference across the TEG modules considering several fin configurations, size, thickness, height, density of fins, material types, etc. of both hot & cold side heat exchangers. The final fin design selection was made based on both the best or optimal heat transfer through the TEG modules & back pressure characteristics and on the manufacturing viability. The stainless steel hot side heat exchanger with nickel fins and aluminum cold side heat exchanger were selected. To make sure that the hot and cold side heat exchangers are in sufficient contact with the TEG modules during the initial bolted assembles and during subsequent heating and cooling, an FEA contact analysis of the TEG system is carried out and results explained. To check the validity of the analytical models, a 200 W modular physical prototype system, scalable to final 1000 W system, with 80 packaged Half-Heusler (HH) TEG modules is built and tested. A total TEG system power output of 220 W and 270 W were measured at a water coolant temperature of 60 [degrees]C and 10 [degrees]C, respectively under the average gas inlet temperature of 550 C at exhaust mass flow rate of 90 g/s exhaust gas. Finally, a 1000 Watt system containing 400 HH TEG modules was built & tested on a diesel engine using 550 C average gas inlet temperatures at exhaust mass flow rate of 450 g/s and 40 C to 60 C coolant temperatures and the system produced a power of 1004 Watts. The measured results validated the analytical model reasonably well.
[1.] Yie Meng Hoi, Chung D.D.L., 'Flexible graphite as a compliant thermoelectric material', Letters to the Editor / Carbon 40 (2002) 1131 -1150
[2.] Yanliang Zhang, Cleary Martin, Wang Xiaowei, Kempf Nicholas, Schoensee Luke, Yang Jian, Joshi Giri, Meda Lakshmikanth; 'High-temperature and high-power-density nanostructured thermoelectric generator for automotive waste heat recovery', Energy Conversion and Management 105 (2015) 946-950
[3.] Martin Cleary, Zhang Yanliang, Meda Lakshmikanth, Wang Xiaowei, Joshi Giri, Yang Jian, Engber Mike and Ma Yi, 'Development of a 200 W Thermoelectric Generator for Exhaust Waste Heat Recovery from a Diesel Engine', International Conference on Thermoelectrics, Nashville, July 6-10, 2014.
[4.] http://www.bergquistcompany.com/ Gap Pad 5000S35
This work is based on funding support from the US Department of Energy and US Army under Award DE-EE0004840.
[R.sub.1] - Convection from hot gas to hot HEX plate/fin base.
[R.sub.2] - Convection from hot gas to hot HEX fin projection.
[R.sub.3] - Conduction through hot HEX fin base.
[R.sub.4] - Conduction through hot HEX plate thickness.
[R.sub.5] - Conduction through hot HEX fin projection.
[R.sub.6] - Conduction to graphite pad.
[R.sub.7] - Conduction through TEG module
[R.sub.8] - Conduction through cold HEX plate
[R.sub.9] - Convection from cold HEX plate to coolant
[R.sub.10] - Convection from cold HEX fin projection to coolant
[R.sub.11] - Conduction through cold HEX fin projection.
[N.sub.f] - Total number of fins in the line (cold or hot).
[K.sub.f] - Fin thermal conductivity.
[K.sub.p] - Plate thermal conductivity.
[t.sub.p] - Plate thickness
[L.sub.c] - Corrected length
[A.sub.c] - Cross sectional area of the fins
P - Perimeter of the fin
m - Efficiency parameter
[[epsilon].sub.f] - Fin efficiency
S - Transverse spacing (free flow width).
H - Free flow height.
t - Fin thickness.
L: - Fin length.
p - gas density
[D.sub.h] - Hydraulic diameter
CFD - Computational Fluid Dynamics
FEA - Finite Element Analysis
TEM - Thermoelectric module
TEG - Thermoelectric generator
HEX - Heat exchanger
Lakshmikanth Meda and Martin Romzek Eberspaecher North America Inc.
Yanliang Zhang Boise State University
Table 1. 200 W System Test performace comparision with 1-D analytical tool predictions I-DTool(C) Module 1 Module 2 Module 3 HotsideTEM 473 448 424 Cold side TEM 75 73 70 [DELTA]T TEM 398 375 354 HotsideTEM 482 460 439 Cold side TEM 133 131 129 [DELTA]T TEM 349 329 310 Water outlet Exhaust outlet Inlet conditions 1-DTool 32 C 443 C 550 C exhaust, 90g/s, Test measurement 28 C 429 C 10 water 1-DTool 104 C 490 C 550 C exhaust, 90 g/s, Test measurement 96 C 492 C 86 C water I-DTool(C) Module 4 HotsideTEM 401 10 C water Cold side TEM 67 inlet [DELTA]T TEM 334 HotsideTEM 419 Cold side TEM 127 86 C water [DELTA]T TEM 292 inlet Measured power (W) 1-DTool 270 W Test measurement 1-DTool Test measurement 228 W Table 2. 1000 W System test performace comparision with 1-D analytical tool prediction 1-DTool(C) Module 1 Module 2 Hot side TEM 479 455 Cold side TEM 98 95 [DELTA]T TEM 381 360 Water outlet Exhaust outlet 1-DTool 62 C 449 C Test measurement 56 C 446 C 1-DTool(C) Module 3 Module 4 Hot side TEM 432 411 Cold side TEM 93 91 [DELTA]T TEM 339 320 Inlet conditions Measured power (W) 1-DTool 553 C exhaust, 458 g/s, 1003W Test measurement 42 C water
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|Author:||Meda, Lakshmikanth; Romzek, Martin; Zhang, Yanliang; Cleary, Martin|
|Publication:||SAE International Journal of Commercial Vehicles|
|Date:||May 1, 2016|
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