Thermodynamic design data for absorption heat transformers—Part II. Operating on water-calcium chloride
Abstract The Gibbs phase rule and the thermodynamic properties of the working pair limit the choice of operating temperatures. For any combination of the temperatures, the concentrations in the absorber and the generator and hence the flow ratio are fixed. For any particular working pair, the coefficient of performance is related to the flow ratio. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for absorption heat transformers operating on water-lithium bromide. The interaction of operating temperatures has been illustrated graphically.
Alternative absorption heat transformer configurations integrated with water desalination system
Abstract Alternative configurations of absorption heat transformer (AHT) systems using LiBr/H2O as the working fluid and integrated with a water purification system are analyzed and optimized thermodynamically. The waste heat from a textile factory is utilized to run the AHT systems and the generated high temperature heat is employed for the purpose of desalination. A computer program is developed in EES (Engineering Equation Solver) to investigate the effects of different parameters on four different configurations of AHT and the desalination system. It is shown that applying different modifications can increase the coefficient of performance (COP) of the AHT and consequently the productivity of the desalination system. The maximum rate of distilled pure water reaches 0.2435 kg/s when waste heat from the condenser is utilized by the evaporator. Finally, the risk of crystallization of LiBr is lowered in the modified configurations.
BIOSYNTHESIS OF DAUNORUBICIN GLYCOSIDES: ANALYSIS WITH BLOCKED MUTANTS
ABSTRACT Daunorubicin (daunomycin; NSC 82151) is an anthracycline antibiotic that is useful in the treatment of human leukemias. Several Streptomyces species accumulate higher glycosides of daunorubicin, which can be converted to daunorubicin by simple hydrolysis. We isolated a number of mutants of a daunorubicin glycoside-producing streptomycete, and found that some were deficient in accumulation of daunorubicin glycosides. One such mutant accumulated no detectable anthracyclines, while other mutants accumulated anthracyclines or aglycones that have not been reported before or have been described as co-metabolites of daunorubicin glycosides. Some of these anthracyclines and aglycones were purified and used as substrates in bioconversion experiments with various mutants. The results allowed us to construct a proposed pathway for the biosynthesis of daunorubicin glycosides by this streptomycete. KEYWORDS Anthracycline; daunorubicin; biosynthesis; blocked mutants; biotransformation.