Human bioclimatic atlas for Mexico

This work presents bioclimatic charts for Mexico, as a result of an analysis of climate for the period 1951–1980. The basis to define the zone of thermal comfort was the equation proposed by Auliciems combined with the bioclimatic chart of Olgyay and the diagram of Givoni for bioclimatic control in buildings. Other tools used to carry out the diagnosis were the equations of Fanger. The results obtained were validated according to the parameters established by the American Society of Heating, Refrigerating and Air-Conditioning Engineering (ASHRAE), for the different climates of Mexico. The climatic data were those reported by 700 climatological stations throughout the country. The charts were developed using the ArcInfo program, in which the conditions of comfort, cool and warm were identified in order to achieve better thermal comfort in buildings and the profitable use of this renewable energy.     

A step‐by‐step application of Sandia method in developing typical meteorological years for different locations in Oman

This paper reports on the development of typical meteorological years (TMYs) for seven different locations in Oman based on measured meteorological data. Depending on the availability of data the TMYs developed using Sandia method used data covering 7–17 years. The method as implemented here in a step‐by‐step procedure with illustrations is made simple. The procedure described herein is computerized and can handle any number of data sets in an easy‐to‐use manner. This should facilitate the development of TMYs for any location where enough data is available. Sensitivity analysis of different weights assigned to different weather parameters shows that Sandia method is highly affected by solar flux even if its weight is reduced by half while the weights of other parameters such as temperature, wind, and relative humidity have less impact on the selection of TMY. Copyright © 2005 John Wiley & Sons, Ltd.     

A simplified model for generating sequences of global solar radiation data for isolated sites: Using artificial neural network and a library of Markov transition matrices approach

The purpose of this work is to develop a hybrid model which will be used to predict the daily global solar radiation data by combining between an artificial neural network (ANN) and a library of Markov transition matrices (MTM) approach. Developed model can generate a sequence of global solar radiation data using a minimum of input data (latitude, longitude and altitude), especially in isolated sites. A data base of daily global solar radiation data has been collected from 60 meteorological stations in Algeria during 1991–2000. Also a typical meteorological year (TMY) has been built from this database. Firstly, a neural network block has been trained based on 60 known monthly solar radiation data from the TMY. In this way, the network was trained to accept and even handle a number of unusual cases. The neural network can generate the monthly solar radiation data. Secondly, these data have been divided by corresponding extraterrestrial value in order to obtain the monthly clearness index values. Based on these monthly clearness indexes and using a library of MTM block we can generate the sequences of daily clearness indexes. Known data were subsequently used to investigate the accuracy of the prediction. Furthermore, the unknown validation data set produced very accurate prediction; with an RMSE error not exceeding 8% between the measured and predicted data. A correlation coefficient ranging from 90% and 92% have been obtained; also this model has been compared to the traditional models AR, ARMA, Markov chain, MTM and measured data. Results obtained indicate that the proposed model can successfully be used for the estimation of the daily solar radiation data for any locations in Algeria by using as input the altitude, the longitude, and the latitude. Also, the model can be generalized for any location in the world. An application of sizing PV systems in isolated sites has been applied in order to confirm the validity of this model.     

西沙地区建筑能耗模拟用典型气象年研究

典型气象年可为建筑节能设计提供必要的气象数据条件.在挑选典型气象年的过程中,通常要具备30 a的气象数据资料,包括如干球温度、太阳辐射、风速、露点温度等.中国南海岛礁地区地面气象观测数据缺失问题严重,特别是太阳辐射数据较难获得.针对这一问题,以西沙地区为例,基于中国气象局提供的近30 a(1985—2014)实测气象数...     

A non-convecting solar pond with a constant energy extraction rate

One of the applications in which a solar pond can be utilized is the industrial process heating. In many heating applications, the heat should be supplied at a constant rate and within certain specified temperature limits. In this paper, the possibility of using a solar pond for such a purpose is studied. The mathematical model presented in a previous paper is modified in the present case to meet the new requirements imposed by the nature of the load and is then used to predict the performance of the pond under these conditions. The idea of using a performance chart is presented. This chart can be used to facilitate obtaining the optimum dimensions of a pond intended for a certain heating application. As the numerical values of the results obtained depend on weather data that are location dependent, the chart given in this paper is for Benghazi, Libya (32.1°N). However, the method presented here can be used to construct a performance chart for any other location.     

Generation of typical meteorological years using genetic algorithm for different energy systems

Computer simulation plays an important role in investigating the thermal/energy performance of buildings and energy systems. In order to reduce the computational time and provide a consistent form of weather data, simulation run with multi-year weather files is generally avoided. In contrast, representative weather data is widely adopted. For developing typical meteorological year (TMY) weather files, Sandia method is one of the commonly adopted approaches. During the generation of TMY, different weighting factors are assigned to some key climatic indices. Currently, the values of weighting factors mainly depend on the researchers' judgement. As these weighting factors can express the relative importance of impact of a particular climatic index on the thermal/energy performance of an energy system, computer simulation using different TMYs may lead to different conclusions. Therefore, it is inappropriate to apply one single TMY for all energy systems. In this study, a novel TMY weather file generator has been developed to link up an optimization algorithm and an energy simulation program. Through four application examples (one air-conditioned building and three renewable energy systems), this weather file generator demonstrated its capability to search optimal/near optimal combinations of weighting factors for generating appropriate TMY for computer simulations of different energy systems.     

Design for comfort in Nigeria — a bioclimatic approach

Most of the previous analyses of climate of Nigeria have been for agricultural use or weather prediction purposes. They have little or no application for building design. This paper examines and analyses the climate of Nigeria with respect to building design parameters — temperature, relative humidity, air velocity and solar radiation, with a view to providing design recommendations for the achievement of physiological comfort. It accesses the current methods of climatic analysis with respect to building design. It then develops bioclimatic charts for various cities for the country using a combination of a general atmospheric circulation model approach and control potential techniques. Finally, design recommendations are then suggested for typical cities in the country.     

Comparison of methods for generating typical meteorological year using meteorological data from a tropical environment

This paper presents the comparison of methods for generating typical meteorological year (TMY) data set using a 10-year period of meteorological data from four stations in a tropical environment of Thailand. These methods are the Sadia National Laboratory method, the Danish method and the Festa and Ratto method. In investigating their performance, these methods were employed to generate TMYs for each station. For all parameters of the TMYs and the stations, statistical test indicates that there is no significant difference between the 10-year average values of these parameters and the corresponding average values from TMY generated from each method. The TMY obtained from each method was also used as input data to simulate two solar water heating systems and two photovoltaic systems with different sizes at the four stations by using the TRNSYS simulation program. Solar fractions and electrical output calculated using TMYs are in good agreement with those computed employing the 10-year period hourly meteorological data. It is concluded that the performance of the three methods has no significant difference for all stations under this investigation. Due to its simplicity, the method of Sandia National Laboratories is recommended for the generation of TMY for this tropical environment. The TMYs developed in this work can be used for solar energy and energy conservation applications at the four locations in Thailand.     

Preparation of psychrometric charts for water vapour in Martian atmosphere

Psychrometric charts for condensing water vapour in Martian atmosphere at four different pressures are presented. The charts are based upon semi-theoretical equations and make use of published physical property data and correlations. The behaviour of the vapour phase is characterised by the Virial Equation of State truncated at the third term. The solubility of gas in water is also considered. The charts are constructed with the dry bulb temperature and absolute humidity scales as the orthogonal axes. Curves of constant adiabatic saturation temperature, constant relative humidity, constant gas specific volume and constant enthalpy deviation are plotted on the charts.     

Electricity end-uses in the residential sector of Brazil

The residential energy consumption has been studied in many countries as it usually accounts for a large percentage of the total energy consumption. Energy end-uses have also been a matter of concern as they can assist energy system planning. The objective of this paper is to assess the actual scenario of electricity consumption and estimate electricity end-uses in the residential sector of Brazil for different bioclimatic zones. The analysis is based on a survey performed by 17 energy utilities enclosing a total of 17,643 houses or flats over 12 states in Brazil. The survey was performed to obtain electricity consumption data for all household appliances found in houses and flats. The electricity end-uses were estimated by performing weighted averages according to the location of the dwellings in each bioclimatic zone. Results indicate that the largest end-uses are for refrigerator and freezer together, which account for about 38–49% of the electricity consumption in dwellings in Brazil. Air-conditioning and electric shower are the end-uses that are more dependent on the climatic conditions. The main conclusion that can be made from the analysis is that air-conditioning should be a major concern in the residential sector of Brazil in the near future as its ownership is still low, but its electricity consumption is already significant mainly over summer.     

A simplification of weather data to evaluate daily and monthly energy needs of residential buildings

Hourly, daily, monthly and annual heating and cooling requirements of a residential building located in Ottawa, Ontario, Canada were estimated, employing ENERPASS as the energy simulation tool, and performing hour-by-hour energy analysis. The following weather data were employed:

1. (i) Ten years (1967–1976) of weather data. The ten-year average of the results is identified as TYA.

2. (ii) A typical meteorological year (TMY) generated using the same ten years of data.

3. (iii) Two different hourly ambient air temperature distributions (T1 and T2) for a typical day in each month. The solar radiation on each surface was estimated using the mean monthly clearness index.

The house use patterns, including heat generation and the thermostat setting, were taken the same when using TYA, TMY, T1 or T2. The analysis was carried out for the house as it is (well insulated and airtight), and for two modifications: one with larger infiltration rate and lower wall thermal resistance, and the other with larger south-facing window area and using super-windows. The results of this study show that the long-range hourly, daily, monthly and annual heating and cooling requirements of a residential building located in a cold climate can be predicted by employing mean daily maximum and minimum temperatures and the mean monthly clearness index for each month. This amounts to substantial savings in computational costs, in either using many years of weather data or generating a TMY for the site. For locations lacking detailed hourly weather data, the use of data and the procedure outlined in this study may be employed to predict the long-range thermal performance of simple residential buildings.     

Simulation of global solar radiation based on cloud observations

A stochastic model for simulating global solar radiation on a horizontal surface has been developed for use in power systems reliability calculations. The importance of an appropriate model for global solar radiation has increased with the increased use of photovoltaic power generation. The global solar radiation shows not only regular yearly and daily variations but also a random behaviour. The yearly and daily variations can be described in a deterministic way while the random behaviour has a high correlation with the state of the atmosphere. The astronomic effects can easily be described mathematical with only some minor simplifications but the atmospheric effects are more complicated to describe. The transmittivity of solar radiation in the atmosphere depends on various factors, e.g. humidity, air pressure and cloud type. By using cloud observations as input for the simulations, the local meteorological conditions can be accounted for. The model is usable for any geographical location if cloud observations are available at the location or at locations with similar climatological conditions. This is especially useful for development countries where long-term solar radiation measurement can be hard to obtain. Cloud observations can be performed without any expensive equipment and have been a standard parameter for many years throughout the world. Standard observations are done according to the Oktas-scale. It is the interval between observations that sets the resolution of the simulation: the observations are normally only every hour or every third hour. The model can easily be combined with cloud coverage simulations, has been proposed, for a more general model. For some calculations higher resolution may be needed. This can be obtained by including a stochastic model for the short-term variations and simple model has been proposed. Errors and limitations of the model are estimated and discussed.     

A new method to develop typical weather years in different climates for building energy use studies

Principal component analysis of 30-year long-term meteorological variables was conducted. Typical principal component years (TPCYs) were determined for Harbin, Beijing, Shanghai, Kunming and Hong Kong representing the five major architectural climates across China: severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter. In each climate zone, the TPCY was compared with the 30 individual years and the widely used typical meteorological year (TMY). The monthly principal component and the predicted total building energy consumption based on the TPCY and TMY were very close to the 30-year long-term mean estimation. TPCY for the 21st century in each of the five cities was also identified using predictions from general climate models. The TPCY approach is a good alternative to the TMY method. Firstly, predicted building energy use from TPCY is closer to the long-term estimation than that from the TMY in different climates. Secondly, because only monthly data are considered, the development of TPCY is much simpler and less time-consuming. This would have important applications in the regular updating of typical weather years for building energy studies and in the assessment of the impact of climate change on energy use in the built environment.     

Present status of fluidised-bed combustion

The worldwide interest in various fluidised-bed combustion systems is surveyed. The stage of development reached towards fully commercial boiler systems using fluidised-beds operating at atmospheric pressure for a range of applications from small shell boilers to power generating units is illustrated, using as specific examples projects based on NCB technology by UK boiler makers. Adaptation of the techniques to lowgrade fuels, tailings, waste incineration and crop drying has been demonstrated.Whilst commercial atmospheric boilers are likely to be operating in the next few years, the development of fluidised combustion at pressure waits on the demonstration by large test rigs that they can be successfully coupled with a gas turbine. Proposed rigs in the USA, Germany and the UK are described.     

A Sub-Atmospheric Solar Distillation Unit

This paper describes the design, manufacture and performance of a new type of solar distillation unit. The unit operates at a pressure below the atmospheric and utilizes a flat-plate collector. The designed unit is intended for an experimental purpose and operates on draw and fill or non-flow basis. The unit can provide distilled water from any available brackish or saline water.

The experimental data obtained from this investigation revealed that the maximum daily productivity of the unit was 5,4kg/(m²/day) and the maximum daily efficiency was 59%.     

A simplified technique to compute spectral atmospheric radiation

The spectral distribution of longwave atmospheric radiation arriving at the earth's surface is composed of contributions from atmospheric layers which absorb and re-emit longwave radiation. A procedure to estimate this radiation requires, as input, the temperature and pressure variations with altitude and the distribution of absorbing gases in the atmosphere. Such detailed information about the atmosphere at a given location and time is rarely known. However, local variation of the amount of water vapor is generally known, and ozone undergoes known seasonal variations. These two gases along with carbon dioxide are the main emitters of longwave radiation in the atmosphere.A rigorous technique to compute spectral atmospheric radiation is used together with atmospheric data from a Standard Atmosphere to examine the variation of spectral emissivity with the amount of absorbing gases in the atmosphere. A simple spectral correlation is thereby developed which is then applied to the other Standard Atmospheres utilizing their water vapor amount as the only input. Results obtained from this correlation are compared with those obtained from detailed computations for each Standard Atmosphere. Good agreement is observed at all the wavelengths considered except in a 1 μm region wherein the differences are somewhat larger. It is demonstrated that for any geographic latitude and season the spectral longwave atmospheric radiation can be computed from a simple correlation using precipitable water vapor amount as the only input parameter.     

Monitoring and control of bottomhole pressure during surge and swab operations using statistical process control

This article for the first time uses a mixture of Statistical Process Control and Engineering Process Control to identify, monitor and control assignable and common causes during drilling operations. To this end, Control charts are applied on the output of the process controlled using EPC and points outside of the predefined control limits are identified. This method can use controllable input variables not used in EPC such as changes in weight of fluid entering the well, to fully control the process. The results show improvements on limits of EPC method using SPC for controlling bottomhole pressure in the acceptable range.     

Thermodynamic analysis,parametric study and optimum operation of the Kalina cycle

The work described here has a major objectives the complete thermodynamic analysis and the parametric study of the Kalina Power Unit. The device layout optimization is based on the presentation of the unit on the T-h and h/T-s thermodynamic charts. The operation of the power unit is simulated by the use of equations describing the thermodynamic behaviour of the NH₃/H₂O mixture. The important parameters of the unit, i.e. high, medium and low pressures/rich, weak, working solution and boiler vapour mass fraction are discussed and related. Correlations are developed which describe the optimum operation of the Kalina cycle. The maximum thermal efficiency, the heat required to drive the unit and the work produced may be directly calculated from analytical functions in terms of the ambient temperature and the low pressure of the units. The maximum theoretical efficiency ranges from 42·7% to 46·6%.     

A general chart for sizing the collectors of solar heating systems

A general chart is developed for calculating the collector area required to provide a prescribed value of the annual load fraction for solar heating systems. The relationship between collector area and annual load fraction can then be easily obtained for specified collector design parameters, load and location. The construction of the chart is based on correlating data generated by the f-chart method. Data of 13 locations in the U.S.A. are considered. The good agreement of the results obtained by the present simple method and the f-chart for both space and combined space/domestic water heating proves that the two methods are almost of the same accuracy. Since the present chart is not location dependent and allows direct comparison of different collectors, it is a very valuable design aid for sizing and selecting solar collectors.