Micro trigeneration system driven with preheated croton oil - A performance and particulate emission study

Transcription

1 PRO-TEM Special Session on Power Generation and Polygeneration Systems Micro trigeneration system driven with preheated croton oil - A performance and particulate emission study Dawei Wu 1, Hongdong Yu 1, Adam Harvey 2, Anthony P Roskilly 1 1 Sir Joseph Swan Centre for Energy Research 2 School of Chemical Engineering and Advanced Materials Newcastle University

2 1.1. The combination of micro trigeneration and biofuels Opportunity Domestic micro trigeneration system is on the brink of wide application Internal combustion engine is a ubiquitous prime mover Biofuels start to be considered as the fuel for trigenerations/chps Problems Utilisation of food crop oils as fuel jeopardizes food security and market Commercial biodiesels from transesterification are not carbon-neutral fuels Running with biofuels causes problems on internal combustion engine

3 1.2. The combination of micro trigeneration and biofuels Some solution concepts Several kinds of high productivity non edible plant oils are considered as fuel Straight plant oils instead of converted biodiesels are tried on engines Lower the high viscosity of straight plant oils for engine with preheating Problems to be tackled with this study Most commercially available micro trigenerations are still driven by the fossil fuels No straight plant oil micro trigeneration prototype available Potential emission hazards from combustion of straight plant oils

4 2.1. Croton oil and its properties Croton megalocarpus tree Common and indigenous tree in east Africa Seeds are 30% oil and 50% protein Fast growing plant and non-edible oil Gas Chromatography (GC) test result The highest linoleticacid (C18-2) weight percentage High content of oxygen Fatty acids wt.% Lauric acid(c12) 0.11 Myristic acid(c14) 0.04 Palmitic acid (C16) 6.23 Polyunsaturated fatty acid (C16-1) 0.11 Octadecanoic acid (C18) 4.37 Oleinic acid (C18-1) 9.95 Linoleic acid (C18-2) Linolenic acid (C18-3) 3.62 Eicosanoic acid (C20) 0.92 Erucic acid (C22) 0.33

5 2.2. Croton oil and its properties Property differences with diesel Low heating value, cetane number of straight croton oil Higher density and viscosity of straight croton oil Larger molar mass of straight croton oil Items Diesel(Gas oil) Raw Croton oil Mass composition(%) C H O Low heating value(mj/kg) Cetane number Density(kg/m3) @353K 864.9@363K 858.0@373K Surfacetension@at323K(N/m) @353K 0.036@363K 0.034@373K Dynamicviscosity(Pa.s) 0.003@323K 0.010@353K 0.008@363K 0.006@373K Molar mass(kg/kmol) Saturated vapor pressure@ 480 K(bar) Saturated vapor pressure at critical temperature(bar) Critical temperature(k)

6 2.3. Viscosity comparison among diesel and plant oils Viscosity change with temperature lifting The dynamic viscosities between diesel and croton oil show bigger difference, which could be more than 10 folds in ambient temperature. After reaching C, the viscosity of croton oil is very close to that of diesel in ambient temperature Viscosity (mpa.s) Croton oil Jatropha oil Sunflower oil Rapeseed oil Gas oil Temperature (degc)

7 3.1. Configuration of micro trigeneration prototype Advantages Carbon neutral and non-edible straight croton oil as fuel Thorough heat recovery from coolant and exhaust Further cooling supply with heat driven absorption refrigerator

8 3.2. Configuration of micro trigeneration prototype Specification YanmarTF120M (4 stroke single cylinder diesel engine, displacement: 0.638l, compression ratio: 17.7) Generator 6.5kWe power output Diffusion absorption refrigerator (ammoniawater solution as working fluid, 200W heat input) Siemens SCADA system as the control centre

9 4. Particulate emission testing facilities Reasons for PM study on biofuel micro trigeneration Gaseous emission of biofuelsis extensively studied, but limited particulate emission study Distributed energy supply systems are directly located in residential areas It is proved that PM samples are more toxic than the PM fraction Testing facilities Horiba MEXA-1000SPCS -detect particulate number in the size range of 23 nm 2.5 um TEOM Series 1000 particulate monitor measure the overall particulate weight below the size of 2.5 um in high time resolution

10 5.1. Performance results Specific fuel consumption (SFC) The SFC of croton oil reaches about 0.365kg/kWh which is about 20% higher than that of the gas oil owing to the relatively lower calorific value of the croton oil No significant SFC change can be observed for the same fuel when the injection temperature is elevated 1.6 ) h W 1.4 /k g 1.2 (k n tio 1 p m u 0.8 s n o c 0.6 l e fu 0.4 ific c 0.2 e p S 0 Specific fuel consumption Gas oil 30 C Gas oil 60 C Croton oil 32 C Croton oil 60 C Croton oil 90 C 0% 10% 25% 50% 75% 100%

11 5.2. Performance results Electricity generation efficiency (EGE) The EGE drops with lower power output, so trigenerationsystems are always expected to run on full capacity instead of low partial loads Running on gas oil, the EGE of the tirgeneration is about % When the croton oil applies, the EGE drops to about % ) 30 (% y c25 n ie fic 20 e n tio 15 ra e n e10 g ity 5 tric c le E 0 Electricity generation efficiency Gas oil (32C) Gas oil (60C) Croton (32C) Croton (60C) Croton (90C) 0% 10% 25% 50% 75% 100%

12 5.3. Performance results Exhaust temperature The elevated injection temperature of the fuels lifts the exhaust temperature The exhaust temperature with the engine running on the croton oil is higher than that on gas oil, which indicates relatively high combustion temperature in the cylinder Exhaust temperature (C) Exhaust temperature Gas oil (32C) Gas oil (60C) Croton (32C) Croton (60C) Croton (90C) 0% 10% 25% 50% 75% 100%

13 5.4. Performance results Energy distribution With Croton oil, the coolant heat Energy distributions of the different fuels in engine full load 25 recovered is decreased owing to its low heat release rate in the cylinder The energy loss increases with higher exhaust temperature The overall efficiency with Croton oil drops, but still in a remarkable high percentage of 76% Energy distribution (kw) Gas oil Gas oil Croton Croton Croton (32C) (60C) (32C) (60C) (90C) Heat loss (kw) Exhaust heat for refrigeration (kw) Exhaust heat for heating (kw) Coolant heat recovered (kw) Power (kw)

14 6.1. Particulate emissions Fine particulate numbers The majority contribution of the particulate number comes from the nucleation mode (<100nm) Without preheating or just preheated to 60 C, the croton oils applied on the engine show a significant boost in the number of the particulates Particulate number #/cm3 4.00E E E E E E E E E+00 Fine particulate numbers of the different fuels Gas oil (32C) Gas oil (60C) Croton (32C) Croton (60C) Croton (90C) 0% 10% 25% 50% 75% 100%

15 6.2. Particulate emissions Fine particulate weight The result indicates that the specific particulate mass of the croton oil is within the band of g/kwh in various loads, which is similar to that of the gas oil, although the majority of the points of the gas oil is lower than 0.6 g/kwh with several exceptional. Fine particulate mass of the different fuels ) 1.60 h 1.40 W /k (g 1.20 s a 1.00 m 0.80 te 0.60 la u 0.40 rtic a p 0.20 e 0.00 in F 0% 10% 25% 50% 75% 100% Gas oil (32C) Croton (90C)

16 7. Conclusions Higher Specific fuel consumptions are observed with croton oil, as its lower heating value. The use of straight croton oil won t largely affect the electricity generation efficiency of the system. The preheating causes the exhaust temperature lifting. The poor heat release rate of croton oil causes the lower coolant heat recovery. The higher exhaust temperature intensifies the heat loss. The significant decrease of PM number with preheating reflects a big improvement of atomization and combustion in the cylinder. The similarity of the PM weight with diesel and croton oil. To meet the strictest PM emission standard for the health concern, after-treatments should be considered.

17 PRO-TEM Special Session on Power Generation and Polygeneration Systems Thank you very much! If you re interested in the prototype, please feel free to contact Dawei Wu via