Analysis of Heat Transfer From a Photobioreactor

2016 ◽  
Author(s):  
Gary A. Anderson ◽  
Sarmila Katuwal ◽  
Anil Kommareddy ◽  
Stephen Gent
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Heat Loss ◽  
Growth Medium ◽  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate ◽  
Medium Temperature ◽  
Reactor Volume ◽  
Light Passing

A photobioreactor (PBR) was operated for sixteen days producing S. Leopoliensis. The PBR was lit by two LED panels, one on each of the long sides of the PBR. The PBR dimensions were nominally 51mm by 273mm with a height of 319mm (273mm liquid depth). Each LED panel was powered at 14.1W (11.2V and 1.26A). Measurements of ambient temperature, ambient relative humidity, water loss from the PBR, relative humidity of the exhaust gas from the PBR, air flow rate through the PBR, air pressure in the plenum, growth medium temperature, and LED panel temperature were made approximately daily. Measurements show that the growth medium (water) temperature was relatively insensitive to the ambient temperature which varied from 22.7C to 33.6C. The medium temperature ranged from 23.9C (beginning of the test) to 40.6C. The medium temperature mirrored the LED panel temperature staying 2–4C below the LED panel temperature after the first day. The elevated LED panel temperature was likely due to the inefficiency of the LED lights and the fact that much of the light passing through the reactor volume was incident on the LED panel on the opposite side of the reactor. The panels are black in color and absorbed a significant portion of the light passing through the reactor volume. The air flow rate through the PBR ranged from 1.33×10−5m3/s to 1.67×10−5m3/s. The parallel between panel temperature and PBR medium temperature indicate that the amount of air moving through the PBR was insufficient to affect the medium temperature significantly. The heat loss from the PBR to the ambient environment was also small likely due to the small area available to heat loss to the environment when the PBR walls with the LED panels are excluded. The LED panels covered nominally 88% of the PBR reactor volume area. The measured data and measurements of light intensity passing through the two short walls of the panel will be used to estimate heat loss parameters of the PBR. The exhaust air from the PBR varied from 42.6% to 99.1% with the higher measurements occurring days 6–11. Estimates of the energy stored in the algal biomass are also evaluated in the analysis.

scholarly journals Batch drying of sliced tomatoes at specific ambient conditions

2018 ◽  
Vol 11 (2) ◽  
pp. 134-140 ◽  
Author(s):  
Mohammad Jafar Royen ◽  
Abdul Wasim Noori ◽  
Juma Haydary
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Flow Rate ◽  
Ambient Pressure ◽  
Air Flow ◽  
Force Sensor ◽  
Effect Of Temperature ◽  
Air Flow Rate ◽  
Ambient Conditions ◽  
Drying Time

Abstract In this work, drying of tomato slices was studied in a laboratory scale batch dryer working at conditions specific for geographical locations with low ambient pressure and low relative humidity of air. Tomato is a perishable farm product with high moisture content. Despite their high value, tomatoes are subjected to wastage and spoilage during their seasonal period; to last longer after harvested, they need to be treated by drying. Drying is one of the most widely used methods of tomato preserving for a longer period of time. This study involves experimental work on tomatoes drying in a tray laboratory batch dryer with the dimensions of (490 × 330 × 310) mm, a load cell-force sensor (range: 0–5 kg), fan (speed: 0–2500 rpm), air flow sensor (0–150 l/min) and a temperature and humidity monitoring system. This study was aimed at the development of a suitable drying method for the production of dehydrated agricultural products under specific air properties and climate conditions such as low ambient pressure and low relative humidity. During the experiment, the average ambient pressure was 82 kPa, and the average relative humidity of air was 20 %. Drying characteristics of tomato slices were determined at three temperature levels, namely: 50 °C, 60 °C and 70 °C,and three air flow rates: 30 l/s, 40 l/s and 50 l/s, for each temperature level. In this study, the effect of temperature, air flow rate, and ambient conditions on the drying rate of tomato slices were studied. The results indicate that during the experiments, tomatoes were dried to the final moisture content of 32.2 % from 92 %. Drying time at 50 °C, 60 °C and 70°C, and air flow of 30 l/s was 17.80 h, 15.80 h, and 14.08 h, respectively. For the air flow rate of 40 l/s, the drying time was 15.0 h, 12.9 h and 11.7 h and for the air flow rate of 50 l/s, the drying time of tomato slices was 14.0 h, 11.6 h and 10.2 h, respectively.

scholarly journals Numerical analysis on the dynamic response of a plate-and-frame membrane humidifier for PEMFC vehicles under various operating conditions

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 641-650 ◽  
Author(s):  
Sungho Yun ◽  
Dowon Cha ◽  
Kang Sub Song ◽  
Seong Ho Hong ◽  
Sang Hun Lee ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Relative Humidity ◽  
Dynamic Response ◽  
Flow Rate ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Acceleration ◽  
Dry Air ◽  
Actual Operating

Abstract PEMFC needs to be maintained at an appropriate temperature and humidity in a rapidly changing environment for automobile applications. In this study, a pseudo-multi-dimensional dynamic model for predicting the heat and mass transfer performance of a plate-and-frame membrane humidifier for PEMFC vehicles is developed. Based on the developed model, the variations in the temperature and relative humidity at the dry air outlet are investigated according to the air flow acceleration. Moreover, the dynamic response is analyzed as a function of the amplitude and period of the sinusoidal air flow rate at actual operating conditions. The effects of heat transfer on the dynamic response are more dominant than those of mass transfer. The settling time of the temperature and relative humidity at the dry air outlet decrease with the increase in air flow acceleration. In addition, the variations in the temperature and relative humidity at the dry air outlet increase with the increases in the amplitude and period of the sinusoidal air flow rate.

scholarly journals Heating Performance Characteristics of an Electric Vehicle Heat Pump Air Conditioning System Based on Exergy Analysis

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2868 ◽  
Author(s):  
Xingwang Tang ◽  
Qin Guo ◽  
Ming Li ◽  
Mingzhe Jiang
Keyword(s):  
Ambient Temperature ◽  
Electric Vehicle ◽  
Flow Rate ◽  
Air Conditioning ◽  
Air Flow ◽  
Exergy Destruction ◽  
Air Flow Rate ◽  
Air Conditioning System ◽  
Heating Capacity ◽  
Expansion Valve

In this paper, a heat pump air conditioning system (HPACS) with refrigerant R134a based on the functional requirements of battery electric vehicle is designed and tested. Experiments were conducted to evaluate the effects of different ambient temperature, air flow rate of internal condenser, expansion valve (EXV) opening and compressor speed. The results demonstrate that air flow rate of internal condenser, EXV opening and compressor speed have important impact on heating capacity, compressor power consumption and coefficient of performance (COP) under several ambient temperatures. To verify the HPACS can also provide the heating capacity required by the battery electric vehicle cabin in cold climate, the system was also tested under a −5 °C ambient temperature, it was found that the heating capacity is 3.6 kW and the COP is 3.2, demonstrating that the system has high energy efficiency. In addition, heating process analysis of the HPACS under lower temperature is studied by exergy principle. The results indicate that compressor is the highest exergy destruction in all components, accounting for 55%. The percentage of exergy destruction in other components is about 28%, 12% and 5% for the expansive valve, condenser, and evaporator. Furthermore, air flow rate of internal condenser, ambient temperature and expansion valve opening have important impact on exergy destruction and exergy efficiency of the HPACS.

scholarly journals Heat Calculations of Water Cooling Tower

2021 ◽  
pp. 173-176
Author(s):  
Abdulkhaev Zokhidjon Erkinjonovich ◽  
Madraximov Mamadali Mamadaliyevich ◽  
Abdurazaqov Axmadullo Muxammadovich ◽  
Shoyev Mardon Axmadjon o’g’li
Keyword(s):  
Relative Humidity ◽  
Flow Rate ◽  
Energy Efficient ◽  
Cooling Tower ◽  
Air Flow ◽  
Aerodynamic Resistance ◽  
Thermal Calculation ◽  
Water Cooling ◽  
Air Flow Rate ◽  
Resistance Thermometer

Annotation: The article discusses the thermal calculation of the cooling tower. In the calculation, the specific air flow rate, the number of sections and the structural size of the tower are determined, according to the calculated value, energy-efficient methods are determined. Keywords: cooling tower, fan, specific air enthalpy, diagram I-d, relative humidity, aerodynamic resistance, thermometer. Аннотация: В статья рассмотрено тепловая расчёт градирня. В расчёта определено удельная расход воздуха, число секция и конструктивный размер градирня, по вычисленных величина определяется энергоэффективный методы. Ключевые слова: градирня, вентилятор, удельная энтальпия воздуха, диаграмма I-d, относительная влажность, аэродинамическое сопротивление, термометр.

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