Factors affecting energy consumption and productivity in greenhouses

Aim of study: To investigate the impact factors affecting the greenhouse environment on energy consumption and productivity. Area of study: Alborz province of Iran during the period 2018–2020. Material and methods: In this study, 18 active units of greenhouse owners in Alborz province of Iran that had necessary standards were identified. Then, upper and lower amplitudes of the variables affecting productivity and energy consumption in greenhouses were calculated using a type-2 fuzzy neural network, Matlab 2017 software. Area, temperature, energy exchange, environmental evapotranspiration and relative humidity were studied as indicators. Main results: With each unit of temperature, energy consumption and productivity increased by 0.737% and 0.741%, respectively; with each unit of energy exchange, they increased by 0.813% and 0.696%, respectively; with each unit of evaporation and transpiration of the environment, they increased by 0.593% and 0.869%, respectively; and with each unit of humidity, they increased by 0.398% and 0.509%, respectively. Research highlights: The factors affecting the greenhouse environment such as area, temperature, evapotranspiration and relative humidity had a significant effect on productivity in studying greenhouses and therefore increasing their productivity. According to the results, the model’s ability in energy consumption was better than that for energy efficiency prediction. Also, greenhouse ranking was done by FAHP method.

The energy meaning of Boltzmann’s constant

The atomic scale is the only relevant thermodynamic scale in our universe, since quantum properties restrict classical considerations of subatomic physics and disappear for larger scales. Then the characteristic energy that dictates the value of the unit of temperature can be the classical thermal energy defined for simplest atoms. It is shown that vibrational frequency of a classical model hydrogen atom, of the radius of its Rydberg wavelength, is in far-infrared range and from its quantum of energy one can obtain the value of Boltzmann’s constant that serves as the measure of the absolute temperature in kelvins.

Realization of new definition of kelvin on National primary state standard of temperature in the temperature range from 0.3 K to 273.16 K GET 35-2021

Description and metrological characteristics are presented of upgraded in 2021 equipment of National primary state standard of temperature on the temperature range from 0.3 K to 273.16 K GET 35-2021. GET 35-2021 allow to to the reproduce and disseminate the unit of temperature according to its definition accepted on 26th CGPM in 2018. Three installations of acoustic gas thermometry developed in 2012–2019 have been introduced in the National primary state standard covering ranges 79–273.16 K, 4.2–80 K, 268.16–273.16 K. The equipment for reproduction of fixed points of of International Temperature scale ITS-90 has been upgraded for uncertainty reduction. Uncertainty of reproduction of thermodynamic temperature and temperature according to ITS-90 have been calculated on the basis of investigations of upgraded equipment.

Temperature and its measurement

Temperature is that property of a body which determines whether it gains or loses energy in a particular environment. In classical thermodynamics temperature is defined by the relationship between energy and entropy. Temperature can be defined only for a body that is in thermodynamic and thermal equilibrium; whilst organisms do not conform to these criteria, the errors in assuming that they do are generally small. The Celsius and Fahrenheit temperature scales are arbitrary because they require two fixed points, one to define the zero and the other to set the scale. The thermodynamic (absolute) scale of temperature has a natural zero (absolute zero) and is defined by the triple point of water. Its unit of temperature is the Kelvin. The Celsius scale is convenient for much ecological and physiological work, but where temperature is included in statistical or deterministic models, only thermodynamic temperature should be used. Past temperatures can only be reconstructed with the use of proxies, the most important of which are based on isotope fractionation.

Evaluation of Tightening Process of Reamer Bolts by Cooled Fitting

Reamer bolts are widely used for the bolted joints subjected to large shear forces. The most important application is the case of clamping rigid flanged shaft couplings which deliver large torques. The body diameter of a reamer bolt is basically equal to the bolt hole diameter. When installing into the joint, reamer bolts are cooled in order to temporarily reduce its diameter for easy insertion. Dry ice or liquefied nitrogen is commonly used to lower the bolt temperature. It is customary in the actual tightening operation that to save working hours, the tightening torque is applied to the reamer bolt while its temperature is still well below the ambient temperature. Accordingly, the reamer bolt inevitably elongates as its temperature increases to the ambient one, which leads to the reduction of axial bolt force. In this paper, an equation of simple form is derived, which can estimate the amount of bolt force reduction occurred during the tightening operation of reamer bolts by cooled fitting. It is shown that the reduction rate in axial bolt stress, per unit of temperature difference between the reamer bolt and the fastened plate, gradually increases as the grip length is increased, ranging from about 1MPa/K to somewhat in excess of 2MPa/K. If the target joint tightened by cooled fitting has an excessive strength, the derived equation is useful from the practical point of view. It can determine the excessive torque that compensates the bolt force reduction due to the elongation during the tightening operation. The effectiveness of the derived equation is demonstrated by experiments. Based on the derived equation and the experimental results, a guide line is proposed to securely tighten reamer bolts using cooled fitting.