鶏舎および畜舎内温度変動の動的解析

抄録

Man has brought many agricultural operations into confinement which modifies the environmental conditions from those occuring naturally. He is now faced with the problem of optimizing production or profit through structural design and management decisions. In order to accomplish this it is desireable to develop methods of accurately predicting the conditions which occur from hour to hour as well as methods to simulate conditions for aid in design.
In order to analyse the thermal environment of animal shelters, a transient method (matrix technique) has been applied (Jordan, et al.. 1968). This method evaluates the periodic responses of animal shelters as influenced by external temperature patterns. However, each harmonic term in a Fourier series representation of the outside weather conditions has to be determined separately.
In the present study, another technique of dynamic simulation (impulse method) has been used. This technique has been found useful for the analysis of greenhouse prior to this study (Takakura, 1967 and 1968). A mathematical model of the system shown in Fig. 1 is developed and the temperature regime of the system is simulated. Considering that temperature is composed of a steady state term and a transient term, the inside temperature of the animal shelter can be expressed as θ_in=θ_n+θ′_in. Where: θ_in is the inside temperature of the animal shelter; θ_in is the steady state term of the inside air termperature; and θ′_in is the transient term of the inside air temperature.
The steady state term is calculated from a fundamental heat balance (that is Eq. (1)) where each component is developed in Eq.(3) through Eq. (6). The component considered are: q_h, the heat transferred from the wall; q_v, the heat transported by ventilation; q_s, the heat transferred from the ground; and q_c, the heat produced by the animals.
The transient term is calculated by impulse technique. The basic equations are presented in Eq. (8) through Eq. (16). Using the Laplace transforms of these equations ((A-1)through (A-7) as shown in Appendix) the weighting function is given in Eq. (A-14). If a forcing function impressed upon the system is expressed as F(t) (in Eq. 17)), the response to the input would be given as R(t) (in Eq. (18)).
The Fourier coefficients of the inside and the outside air temperature calculated from the observed data are presented in Table 1. The calculated temperatures and the observed temperatures are shown in Figs. 2 and 3. The results are in good aggreement. From the present analysis, it is concluded that impulse techniques as well as matrix techniques are useful in simulation of the thermal environment of animal shelters. Previous work indicates the application to greenhouse simulation. Therefore it is concluded that these techniques have considerable generality.
The present study was conducted at University of Minnesota, where the senior author had the previlege of working with the other authors on post-doctsral studies. The computer time was supported through a grant from the University of Minnesota Computer Center and is greatfully acknowledged. The experimental data taken in a 5000 bird laying house in North Carolina, USA, was graciously supplied by Dr. Jordan.