Pengaruh Suhu dan Kelembaban Terhadap Rasio Kelembaban dan Entalpi (Studi Kasus: Gedung UNIFA Makassar)

Temperature affects humidity. The interaction of temperature and humidity also directly affects the health and well-being of humans. The relative humidity (RH) of the air is an indication of how much water vapor is in the air at a particular temperature compared with how much water vapor the air could actually hold at that temperature. Air at 100 % relative humidity holds the maximum amount of water possible at that particular temperature and is said to be saturated. Therefore, air at 50% relative humidity, regardless of temperature, is holding half of its total possible water capacity. In essence, cold air cannot hold as much water vapor as warm air. In a closed environment such as a display case, there will be a fixed amount of water vapor, referred to as the absolute humidity. If the temperature inside the case falls then the relative humidity will rise. If the temperature rises the relative humidity will fall. Such changes in relative humidity could be caused by many factors including direct sunlight, spotlights and air-conditioning failures. Research carried out by experimental studies that we can get the humidity ratio and specific enthalpy in a kind of rooms either using The Psychrometric Chart and The formula. The specific humidity or humidity ratio of an air sample is the ratio of the weight of water vapor contained in the sample compared to the weight of the dry air in the same sample. Enthalpy is the amount of heat (energy) in the air per unit mass. Enthalpy is the total amount of energy present in the air, both from air and water vapor contained therein. And, Specific enthalpy of moist air is defined as the total enthalpy of the dry air and the water vapor mixture - per unit mass of dry air. Keywords: Temperature; Relative Humidity; Humidity Ratio; Specific Enthalpy.

Filmwise Condensation From Humid Air On a Vertical Superhydrophilic Surface: Explicit Roles of the Humidity Ratio Difference and the Degree of Subcooling

The process involving heat and mass transfer during filmwise condensation (FWC) in presence of non-condensable gases (NCG) has great significance in a large variety of engineering applications. The vapor mass flux leading to condensation and the resulting condensation heat transfer coefficient (CHTC) are dependent on the gradients of temperature and vapor mass fraction established near the condenser plate. The effects of the two most influencing thermodynamic parameters, i.e., the degree of subcooling and the difference of humidity ratio (between the free stream environment and on the condenser plate), have been characterized in this work both experimentally and through a mechanistic model. The vapor mass flux during condensation on a subcooled vertical superhydrophilic surface under a free convection regime is experimentally measured in a controlled environment (temperature and humidity) chamber. A mechanistic model, based on the similarity of energy and species transports, is formulated for the thermogravitational boundary layer over the condenser plate and tuned against the experimental results. Further, the model is used to obtain comprehensive data of the condensate mass flux and CHTC as functions of the salient thermal operating conditions over a wide parametric range. Results indicate that humidity ratio difference has a more pronounced influence on the condensation mass transfer rather than the degree of subcooling. The mechanistic model lends to the development of empirical correlations of condensate mass flux and CHTC as explicit functions of these two parameters for easy use in practical FWC configurations.

Effect of Post-Drying Tempering of Rice on Minimizing Kernel Fissuring and Maximizing Moisture Removal

HighlightsMore moisture can be removed in a single drying pass without severely fissuring kernels when samples are tempered than when immediately cooled without tempering.Tempering rice kernels immediately after drying can reduce the percentage of fissured kernels by up to half of that when kernels are immediately cooled without tempering.Abstract. Improper rice drying results in kernel fissuring, leading to head rice yield reduction due to breakage during milling. The objective of this study was to determine the percentage points (pp) of moisture content (MC) reduction that can be achieved in a single drying pass without significantly fissuring kernels. Long-grain rough rice of cultivars CL XL745 and Diamond at initial MCs of 18%, 17%, 16%, 15%, and 14% were dried using air at 45°C/20% relative humidity (RH), 50°C/15% RH, 55°C/12% RH, 60°C/10% RH, and 65°C/8% RH to MCs of 17%, 16%, 15%, 14%, 13%, or 12% with and without post-drying tempering. All temperature/RH combinations resulted in a humidity ratio of 0.012 kg water kg-1 dry air. Tempering was conducted at the drying air temperature for 4 h. The resulting samples achieved between 1 and 7 pp of MC reduction in a single drying pass. The pp of MC reduction that can be attained in a single drying pass without causing significant fissuring varied across the cultivars tested. Generally, ~2 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~4 pp for Diamond without causing adverse fissuring when samples were not tempered after drying. However, with tempering, ~3.5 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~5.5 pp for Diamond without causing significant fissuring. However, these amounts varied depending on the drying air conditions and initial MC. For both cultivars, tempering immediately after drying reduced the fissured kernel percentage by up to half of that when the kernels were not tempered. These findings quantify the importance of rice tempering and provide information on how much moisture can be safely removed in a single drying pass. Such findings may be applied to different dryer types to reduce fissuring due to drying, thereby minimizing head rice yield reductions. Keywords: Drying, Glass transition, Rice quality, Single-pass drying, X-ray imaging.

A Numerical Investigation on Emissions of Partially Premixed Shale Gas Combustion

The adiabatic, turbulent, and partially premixed combustions of several shale gases and air in a co-axial type combustor are computationally examined under the effects of different equivalence ratios, inlet temperatures, flow rates, humidity ratios, pressure, oxid inlet temperatures and flow rates, and swirl velocities in this study. Shale gases are extracted from Barnette, New Albany, Fayetteville, and Haynesville areas of USA. ANSYS software is used for numerical calculations of combustion. Results show that the maximum NO emissions for Barnette, New Albany, Fayetteville, and Haynesville shale gas occur at the equivalence ratio of 1.42, 1.41, 1.4, and 1.39. The rising fuel inlet temperature increase NO and reduces CO emissions after 300 K. The increasing humidity ratio causes NO and CO mass fractions to decrease. The ascending pressure raises NO up to 4 bar and lowers CO emissions. The increasing oxid flow rate abates the mass fractions of both NO and CO. The rising swirl velocity escalates NO up to 15 m/s and decreases CO emissions for all the shale gas combustions.

DESIGN AND FABRICATION OF PORTABLE ATMOSPHERIC WATER SEQUESTRATOR AS AN OFF-GRID WATER SYSTEM

The lack of access to clean water has been one of the major issues in water-stressed countries. In this study, the design and fabrication of a prototype portable atmospheric water sequestrator device was carried out and tested for its ability to harness available water vapor in the atmosphere. The system utilized the concept of Peltier effect in Peltier units as a new way to liquefy atmospheric water. MATLAB® was used to investigate effects of different parameters namely humidity ratio, volumetric air flow rate, and Peltier surface temperature on water generation. Results showed that humidity ratio exhibited the highest significance among the parameters. Furthermore, the highest water production was found to be 7.643 mL at a Peltier surface temperature of 4 ºC, air flowrate of 24 ft3/min, and humidity ratio of 0.021. Moreover, the physico-chemical characteristics of the water produced was well under the Philippine standards and can be classified into Public Water Supply Class I. KEYWORDS: Design and fabrication, portable water sequestrator, Peltier effect, water generation

Modelling and performance evaluation of a novel disk-type liquid desiccant air dehumidifier with no film flow

A liquid desiccant air dehumidifier (LDAD) with both high efficiency and low desiccant carryover is of vital significance to indoor environment. However, the instability introduced by desiccant film flow tends to deteriorate the droplets entrainment in product air and remains to be solved. In this study, a novel disk-type liquid desiccant air dehumidifier with no film flow (DLDAD) was developed to radically eliminate the apparent desiccant film flow. The distribution and refreshing of liquid desiccant on wetted surface is realized by the rotation of the disks rather than the film flow of liquid desiccant. The performance of DLDAD was numerically evaluated under varied dehumidifier parameters, including stage number, immersion depth, rotation speed and air and solution parameters. The results show that an increase in the stage number can increase dehumidification performance, ensuring the air outlet humidity ratio below 10 g/kg. The dimensionless immersion depth of 0.4 and the rotation speed of 3 r/min are suggested for better dehumidification performance in this case. Increasing solution concentration or decreasing solution temperature can effectively reduce the air outlet humidity ratio. All these results can support the structural design and practical application for LDADs with higher efficiency and lower desiccant carryover in the future.

Experimental Study of Dehumidification Process by CaCl2 Liquid Desiccant Containing CuO Nanoparticles

A conditioning dehumidifier system is a simple technology to improve air quality and also reduces air conditioning costs. This experimental study evaluated the performance of a liquid desiccant system by adding copper oxide nanoparticles (NPs). The effect of operating parameters, such as inlet air humidity ratio and desiccant flow rate on air dehumidification rate, was also investigated. The desiccant solution contained 48[Formula: see text]wt.% CaCl2 and 0.35[Formula: see text]vol.% of CuO NPs. Comparison of liquid desiccants demonstrated a mean difference of 4.5[Formula: see text]g/s[Formula: see text][Formula: see text][Formula: see text]m2 in the air dehumidification rate by solutions with and without CuO NPs.