Increasing the efficiency and generated electricity of organic rankine cycles by using zeotropic mixtures as working fluids

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.We present a systematic and comparative study of the potential of zeotropic mixtures as working fluids in ORCs, considering most of the commonly used hydrocarbon and siloxane substances as components in various concentrations. We investigate the impact on the operation, the efficiency and power output of an ORC. The ORC cycle is realistically simulated in steady state conditions, taking into account all elements of an actual cycle (including an internal heat exchanger). By performing a pinch analysis, the power output is maximized, given the heat profiles of both the heat source and heat sink. The use of suitable zeotropic mixtures as working fluids has a positive effect on the ORC performance in all investigated cases. The potential increase in cycle efficiency and generated electricity is larger for lower temperature heat sources and when the temperature drop over the heat source exchanger is larger. When the ORC is optimized for operation with a low temperature heat source, the potential for increase in electricity production (maximum reported value approximately 23%) by using mixtures is particularly remarkable.dc201

Overview of biologically digested leachate treatment using adsorption

Biological process is effective in treating most biodegradable organic matter present in leachate; however, a significant amount of ammonia, metals and refractory organic compounds may still remain in this biologically digested leachate. This effluent cannot be released to receiving bodies until the discharge limit is met. Several physical/chemical processes have been practiced as post-treatment to remove the remaining pollutants including coagulation–flocculation, oxidation and adsorption. Adsorption is often applied in leachate treatment as it enhances removal of refractory organic compounds. This chapter will focus on works related to adsorption as one of the commonly used methods to treat biologically digested leachate further down to acceptable discharge limit

Overview of biologically digested leachate treatment using adsorption

Biological process is effective in treating most biodegradable organic matter present in leachate; however, a significant amount of ammonia, metals and refractory organic compounds may still remain in this biologically digested leachate. This effluent cannot be released to receiving bodies until the discharge limit is met. Several physical/chemical processes have been practiced as post-treatment to remove the remaining pollutants including coagulation–flocculation, oxidation and adsorption. Adsorption is often applied in leachate treatment as it enhances removal of refractory organic compounds. This chapter will focus on works related to adsorption as one of the commonly used methods to treat biologically digested leachate further down to acceptable discharge limit

Houten-Zuid 'Het archeologisch onderzoek op terrein 21'

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Impact of the frozen vegetable processing chain on health-related compounds : a pilot-scale case study on leek (Allium ampeloprasum var. porrum)

The impact of pretreatment (i.e., unblanched vs. flash-blanched for 90 s at 70°C), freezing rate (i.e., −0.01, −6.25, −7.5, or −10°C/min), storage (i.e., 16 weeks at −15°C), and thawing (i.e., via microwaves, at 20°C, 7°C, or 4°C) on vitamin C and S-alk(en)yl-L-cysteine sulfoxides (ACSOs) stability was evaluated in diced leeks on pilot-scale. In unblanched, diced leeks, >70% of vitamin C was lost during frozen storage and enzymatic conversions of vitamin C and ACSOs could occur further during thawing, independent from thawing method. In this context, flash-blanching showed potential to ensure compound stability through frozen storage and thawing, without indicating major tissue damage (i.e., drip loss). Although flash-blanching reduced the initial vitamin C concentration by 36%–39%, these samples showed 39%–60% higher vitamin C concentrations at the end of storage. ACSOs stability through frozen storage seemed not to be impacted by flash-blanching. Large variability in ACSOs concentrations between samples was observed. This was attributed to deviations in the industrial-relevant cut of 40% white and 60% green, which could have overshadowed certain effects. Furthermore, the freezing rate did not affect the stability of vitamin C and ACSOs during frozen storage of flash-blanched diced leeks. Additionally, no differences in drip loss of flash-blanched diced leeks frozen at different rates were observed. Quick-freezing to a higher end temperature could open perspectives for reducing energy up to 26% (theoretical simulation). However, this should be balanced with product temperature increase after individual quick freezing (IQF) and before bulk storage.The impact of pretreatment (i.e., unblanched vs. flash-blanched for 90 s at 70°C), freezing rate (i.e., −0.01, −6.25, −7.5, or −10°C/min), storage (i.e., 16 weeks at −15°C), and thawing (i.e., via microwaves, at 20°C, 7°C, or 4°C) on vitamin C and S-alk(en)yl-L-cysteine sulfoxides (ACSOs) stability was evaluated in diced leeks on pilot-scale. In unblanched, diced leeks, >70% of vitamin C was lost during frozen storage and enzymatic conversions of vitamin C and ACSOs could occur further during thawing, independent from thawing method. In this context, flash-blanching showed potential to ensure compound stability through frozen storage and thawing, without indicating major tissue damage (i.e., drip loss). Although flash-blanching reduced the initial vitamin C concentration by 36%–39%, these samples showed 39%–60% higher vitamin C concentrations at the end of storage. ACSOs stability through frozen storage seemed not to be impacted by flash-blanching. Large variability in ACSOs concentrations between samples was observed. This was attributed to deviations in the industrial-relevant cut of 40% white and 60% green, which could have overshadowed certain effects. Furthermore, the freezing rate did not affect the stability of vitamin C and ACSOs during frozen storage of flash-blanched diced leeks. Additionally, no differences in drip loss of flash-blanched diced leeks frozen at different rates were observed. Quick-freezing to a higher end temperature could open perspectives for reducing energy up to 26% (theoretical simulation). However, this should be balanced with product temperature increase after individual quick freezing (IQF) and before bulk storage.A