Experimental air conditioning energy evaluation under Caribbean climate conditions.

A 23 factorial design was performed to analyze the performance of a mini-split air conditioning system under several psychrometric air conditions at the evaporator inlet, similar to Tropical Caribbean region conditions. In addition, a search for new energy-saving opportunities was performed. The results showed that interactions between the temperature of the air inlet, the humidity of the air inlet, and the fan speed level are significant in the mini-split energy performance under Caribbean climate conditions. Hence, working on an oriented energy savings control strategy is necessary. Therefore, this study recommends developing a fan speed control scheme, generating energy savings of around 10% in the air conditioning unit.

Experimental data for an air-conditioning system identification.

In this article, data from a 3.5kW mini split air conditioning is presented. A screening 23 design experiment was performed to evaluate the effects of indoor air temperature, absolute humidity and evaporator fan speed in the performance of the air conditioning. This dataset also includes noise factors as outdoor air temperature, fans energy consumption and response as indoor air exit conditions.

Thermal Optimization of a Dual Pressure Goswami Cycle for Low Grade Thermal Sources.

This paper presents a theoretical investigation of a new configuration of the combined power and cooling cycle known as the Goswami cycle. The new configuration consists of two turbines operating at two different working pressures with a low-heat source temperature, below 150 °C. A comprehensive analysis was conducted to determine the effect of key operation parameters such as ammonia mass fraction at the absorber outlet and boiler-rectifier, on the power output, cooling capacity, effective first efficiency, and effective exergy efficiency, while the performance of the dual-pressure configuration was compared with the original single pressure cycle. In addition, a Pareto optimization with a genetic algorithm was conducted to obtain the best power and cooling output combinations to maximize effective first law efficiency. Results showed that the new dual-pressure configuration generated more power than the single pressure cycle, by producing up to 327.8 kW, while the single pressure cycle produced up to 110.8 kW at a 150 °C boiler temperature. However, the results also showed that it reduced the cooling output as there was less mass flow rate in the refrigeration unit. Optimization results showed that optimum effective first law efficiency ranged between 9.1% and 13.7%. The maximum effective first law efficiency at the lowest net power (32 kW) and cooling (0.38 kW) outputs was also shown. On the other hand, it presented 13.6% effective first law efficiency when the net power output was 100 kW and the cooling capacity was 0.38 kW.

Yucca (Manihot esculenta Crantz) starch polysaccharide dextrination through biological procedures

El proceso de dextrinación del almidón de la yuca (Manihot esculenta) utilizando Aspergillus niger fue evaluado a fin de obtener azúcares fermentables a partir del polisacárido original. La concentración máxima de glucosa (2466mg·l-1) se obtuvo a 30ºC en un período de tres días. El análisis estadístico (P=0,05) de los resultados experimentales reveló un comportamiento de segundo orden para el proceso. La interacción entre las variables tiempo y temperatura afectaron significativamente la producción de glucosa debida a la acción enzimática de A. niger sobre el sustrato. El análisis de la superficie de respuesta mostró un punto óptimo para el proceso en 37ºC y 2,75 días, y una interacción significativa entre tiempo y temperatura. Se concluye que la acción catalítica de A. niger depende fuertemente de las condiciones ambientales en las que se desarrolla el proceso.

Cinética de la transesterificación de la oleína de palma africana con etanol / Kinetics of african palm olein transesterification with ethanol

Se estudió la cinética de la reacción de transesterificación de la oleína de palma africana con etanol y las variables que afectan las condiciones del proceso. Se determinó que el mecanismo de reacción que corresponde a este proceso consta de tres etapas reversibles por medio de las cuales se parte de triglicéridos y alcohol hasta obtener éster y glicerina, teniendo como productos intermedios la formación de monoglicéridos y diglicéridos de los distintos ácidos grasos presentes en el aceite. Se determino cual es la influencia de la temperatura sobre las constantes de velocidad, encontrando que el modelo que mejor se ajusta es el de segundo orden y que ésta afecta principalmente la dinámica de formación de mono y diglicéridos, de tal modo que a mayor temperatura se generan menores concentraciones finales de estos productos intermedios.