Optimal waste stream discharge temperature selection for dryer operations using thermo-economic assessment

A typical drying process that has liquid and gas discharge streams has been analysed and the impact of selecting various combinations of soft temperatures on heat recovery, utility targets, area targets, capital cost and total cost is reported. The method is based on the plus-minus principle and traditional pinch analysis methods for utility, area and capital cost targeting with the modification of using a ΔT contribution. Results show that there is significant benefit from optimising discharge temperatures for total cost. To achieve minimum energy consumption and total cost, heat recovery from the dryer exhaust air is necessary. Heat recovery from liquid heat sources is shown to be preferable over gas streams due to a higher film coefficient resulting in less heat exchanger area and capital cost. There is also value in making process modifications, such as combining streams or removing small streams to be solely heated by utility, to reduce the number of network heat exchangers. For the best case, the discharge temperatures of the leaving streams are 18.0 °C for water condensate (liquid stream) and 52.4 °C for the exhaust air (gas stream)

Minimising energy use in milk powder production using process integration techniques

Spray drying of milk powder is an energy intensive process and there remains a significant opportunity to reduce energy consumption by applying process integration principles. The ability to optimally integrate the drying process with the other processing steps has the potential to improve the overall efficiency of the entire process, especially when exhaust heat recovery is considered. However, achieving the minimum energy targets established using pinch analysis results in heat exchanger networks that, while theoretically feasible, are impracticable, unrealistic, contain large number of units, and ultimately uneconomic. Integration schemes that are acceptable from an operational point of view are examined in this paper. The use of evaporated water is an important factor to achieve both energy and water reductions. The economics of additional heat recovery seem favourable and exhaust heat recovery is economically justifiable on its own merits, although milk powder deposition should be minimised by selecting an appropriate target temperature for the exhaust air. This will restrict the amount of heat recovery but minimise operational risk from heat exchanger fouling. The thermodynamic constraints caused by the operating temperatures of the dryer and the poor economics exclude the use of heat pumps for exhaust heat recovery in the short to medium term

Optimal stream discharge temperatures for a dryer operation using a thermo-economic assessment

The application of traditional pinch analysis to processes involving waste streams require the discharge temperatures of the waste streams to be estimated prior to performing the pinch analysis

Total site targeting with stream specific minimum temperature difference

The paper focuses on extending traditional Total Site Integration methodology to produce more meaningful utility and heat recovery targets for the process design. The traditional methodology leads to inadequate results due to inaccurate estimation of the overall Total Site heat recovery targets. The new methodology is a further development of a recently extended traditional pinch methodology. The previous extension was on the introduction of using an individual minimum temperature difference (δTmin) for different processes so that the δTmin is more representative of the specific process. Further this paper deals with stream specific δT min inside each process by setting different δT contribution (δTcont) and also using different δTcont between the process streams and the utility systems. The paper describes the further extended methodology called stream specific targeting methodology. A case study applying data from a real diary factory is used to show the differences between the traditional, process specific and stream specific total site targeting methodologies. The extended methodology gives more meaningful results at the end of the targeting with this avoiding the over or under estimated heat exchanger areas in the process design

The QCD phase diagram at nonzero baryon, isospin and strangeness chemical potentials: Results from a hadron resonance gas model

We use a hadron resonance gas model to study the QCD phase diagram at nonzero temperature, baryon, isospin and strangeness chemical potentials. We determine the temperature of the transition from the hadronic phase to the quark gluon plasma phase using two different methods. We find that the critical temperatures derived in both methods are in very good agreement. We find that the critical surface has a small curvature. We also find that the critical temperature's dependence on the baryon chemical potential at zero isospin chemical potential is almost identical to its dependence on the isospin chemical potential at vanishing baryon chemical potential. This result, which holds when the chemical potentials are small, supports recent lattice simulation studies. Finally, we find that at a given baryon chemical potential, the critical temperature is lowered as either the isospin or the strangeness chemical potential are increased. Therefore, in order to lower the critical temperature, it might be useful to use different isotopes in heavy ion collision experiments.Comment: 7 pages, 15 figure

On The Irrelevance Of Transformational Grammar To Second Language Pedagogy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98173/1/j.1467-1770.1969.tb00467.x.pd

Temperature phase transition and an effective expansion parameter in the O(N)-model

The temperature phase transition in the N-component scalar field theory with spontaneous symmetry breaking is investigated in the perturbative approach. The second Legendre transform is used together with the consideration of the gap equations in the extrema of the free energy. Resummations are performed on the super daisy level and beyond. The phase transition turns out to be weakly of first order. The diagrams beyond the super daisy ones which are calculated correspond to next-to-next-to-leading order in 1/N. It is shown that these diagrams do not alter the phase transition qualitatively. In the limit N goes to infinity the phase transition becomes second order. A comparison with other approaches is done.Comment: 28 pages, 5 figures, corrected for some misprints, unnecessary section remove

The Phase Diagram of Four Flavor SU(2) Lattice Gauge Theory at Nonzero Chemical Potential and Temperature

SU(2) lattice gauge theory with four flavors of quarks is simulated at nonzero chemical potential $\mu$ and temperature $T$ and the results are compared to the predictions of Effective Lagrangians. Simulations on $16^4$ lattices indicate that at zero $T$ the theory experiences a second order phase transition to a diquark condensate state. Several methods of analysis, including equation of state fits suggested by Chiral Perturbation Theory, suggest that mean-field scaling describes this critical point. Nonzero $T$ and $\mu$ are studied on $12^3 \times 6$ lattices. For low $T$, increasing $\mu$ takes the system through a line of second order phase transitions to a diquark condensed phase. Increasing $T$ at high $\mu$, the system passes through a line of first order transitions from the diquark phase to the quark-gluon plasma phase. Metastability is found in the vicinity of the first order line. There is a tricritical point along this line of transitions whose position is consistent with theoretical predictions.Comment: 42 pages revtex, 25 figures postscrip

Minimal Schemes for Large Neutrino Mixings with Inverted Hierarchy

Existing oscillation data point to nonzero neutrino masses with large mixings. We analyze the generic features of the neutrino Majorana mass matrix with inverted hierarchy and construct realistic {\it minimal schemes} for the neutrino mass matrix that can explain the large (but not maximal) \nu_e - \nu_mu mixing of MSW-LAM as well as the nearly maximal \nu_mu - \nu_tau mixing and the small (or negligible) \nu_e --> \nu_tau transition. These minimal schemes are quite unique and turn out to be extremely predictive. Implications for neutrinoless double beta decay, tritium beta decay and cosmology are analyzed.Comment: Refs adde