This paper deals with the theoretical relations between the blowback into the crankcase and the performance of industrial and farm use small two-stroke cycle engines of Schüurle type with some types of cylinder ports.
In order to carry out systematic investigations of the above mentioned, we made cycle simulations of the delivery and the scavenging processes.
The simulations were conducted in the following cases.
1. (a); Inlet pipe, exhaust pipe and scavenging passage were neglected,
(b); inlet pipe, exhaust pipe and scavenging passage (as pipe) were considered, and
(c); inlet pipe, exhaust pipe and scavenging passage (as volume) were considered.
2 Three conditions of perfect stratification, perfect diffusion and half diffusion were considered.
3. (a); Variable values of adiabatic indices were used,
(b); the vaporization of gasoline was considered or not, and
(c); the heat conduction from the wall of cylinder and piston to the mixture gas considered or not.
The conclusions obtained by the investigations (1, 2, 3) above mentioned are as follows.
(1) In the first, (c) is the nearest to the condition of the actual engines.
(2) In the second case, the condition between perfect diffusion and half diffusion is near to that of the actual engines.
(3) In the third case, the influence to the engine performance of the modification is the most at (c).

View full abstract

In this report, pressure losses based on pipe arrangement of the hydraulic circuit used were computed using the two equations, i. e., the one is Weisbach's epuation which was applied in the field of hydraulics since a long time ago, and the other is Ito's equation. As to the latter an equation has been made and its achievements have been highly rated. From these calculation results the outlines of pressure loss were comprehended quantitatively. Moreover, these two old and new methods were compared and their adaptability to the hydraulic circuit were discussed.
The summary of results is as follows;
1. Constant loss elements, such as the low pressure line filter and the oil cooler were important in the hydraulic circuit. Therefore, extreme care must be taken to the selection of it.
2. As to the loss elements related to flow rate in a pipe, the more the load pressure increased, the more the pressure loss decreased, because the flow rate became smaller according to the control principle of this system. Judging from the aspects of presssure loss, it was evident from these results that our control method was desirable.
3. Concerning the relation between pump input speed and pressure loss, the loss tended to increase in proportion to the flow rate as the pump speed became higher. Especially, the rate of increase in low pressure range became larger. Therefore, such a countermeasure as to make the pump input speed smaller at the light operating load must be prepared.
4. Flow in a pipe was almost laminar flow except for a few combinations of high speed and light load in the high and low pressure pipe line. It was evident from these results that the design and layout of pipe line was proper.
5. As described in the paragraph 2. flow rate decreased inversely to the load pressure. Therefore, Reynolds number generally became smaller as the load pressure became larger. Consequently, comparing Weisbach's equation with Ito's one, there was no remarkable difference at the heavy load. From the facts described above, we may conclude that a rigorous treatment in the field of fluidmechanics is unnecessary in the case of this control system.
6. The calculation results of input shaft horsepower of the pump also agreed very well with the experimental one of the engine system which had been described in the previous report. Therefore, it was proved that the calculated values of pressure loss were quantitatively in the right range.
Considering above results on the basis of the equations to be used in this paper, we can generally make the following statement; the pressure loss in this circuit was smaller contrary to our initial estimates. This is based on the reason why we could design an ideal layout on account of the bench test But, in the case of mounting on farm tractor, we shall naturally encounter the space restrictions. Therefore, it seems that actual pressure loss becomes larger.

View full abstract

The applicability of theoretical equation of camber thrust, based on the theory of E. Fiala, to the side force at any side slip angle between 0° and 90° on the tractor tire was investigated using an apparatus mounted with smooth on agricultural tire.
Main results were as followes:
1. The relation between side force (S) included camber thrust and side slip angle (β) was expressed as follows:
When 0°≤β≤β_n,
S={-a₀C/3+Ctanβ-C²tan²β/3f+a₀C(2-μ/f)+C³tan³β/3(3f+a₀C)²(3-2μ/f)}W
and when β_n<β≤90°,
S={μ-a₀C/3(1-μ/f)}W
β_n=tan^-1(3f+a₀C/C), a₀=l/2rsinγ, f=coefficient of maximum friction, μ=coefficient of dynamic friction, W=supporting weight, C=a factor of cornering coefficient, r=radius of tire, l=length of ground contact of tire, γ=camber angle.
2. Using the chi-square test, the hypothesis that the side force calculated from the theoretical equation was equal to the experimental value of both rolling ahd driving wheel is acceptable at a level of 0.01.
3. Variations of the value of C affected by camber thrust was not so large at rolling wheel and positive camber angle of driving wheel but large with increase of negative camber angle of driving wheel and there was a peak camber angle. between -15° and -18°
4. Coefficient of camber thrust of smooth tire was the same value as that of automobile tire and larger than that of agricultural tire.
5. The side slip angle which made side force to zero by the operation of camber thrust became so small as one-tenth of the camber angle and the value was larger than that of automobile tire.

View full abstract

The observation of the trajectory locus of any point on the periphery of the powerd wheel is more important to mimimize the repuired energy for the trafficability of the vehicle.
In this paper the locus of any point on the powered wheel periphery was discussed the retically and experimetally. A small electric bulb was atached on the wheel rim, and its motion was observed by taking the picture of that locus during the experiments in the dark room. Those pictures obtained from the experiments were compared with the ones determined theoretically for various slippages. The comparison of those two locuses were quite satisfactory, especially in the range of the slippage from 30% up to 60%. The experimental formulae determined in the previous reports were validated at slippage less than 87.05%.

View full abstract

On the basis of the experimental results about the frequency response of the operator-tractor control system (Part II), the transfer function model was assumed such as the feedback control system and the constants of each element that composed of this system were determined with the least square method.
And from above results, the steering control response of the operator and the following performance to the course were discussed.
(1) Within the range of ω₀=5 rad/sec (ω₀:the fundamental frequency of the course), the steering control transfer function model of the operator can be described with the first differential element, the first order lag element and the dead time element.
(2) The time constants of the first order lag at the steering control (T₁) are in inverse proportion to ω₀, but their fluctuations increase rapidly out of range of ω₀=2 rad/sec.
(3) The accuracy on the forecast go down with the increase of ω₀, but the forecast are compensated by the steering control operations, such as the loop gain (K₀K₁K₂K₃) nearly equal 1.0, and overall of system is kept in the optimal condition.
(4) The time constant (T₂) of the secondary forecast increase according with the increase of T₁, but T₂ shows the tendency to reach the constant value (nearly 1.0 sec) out of range of T₁=2, 0 sec.
On the case of T₁>2.0 sec, the operasor is possible to follow up the course by only the steering operations according to the frequency of the course, without the special efforts.
When ω₀ is within range of 0.5 and 2.0 rad/ sec (T₁=2.0-0.5 sec), the following of the the course can be kept with that the operator decreases T₁ from 2.0 to 0.5 sec, but as ω₀ is over range of 2.0 rad/sec, the following of the course is very hard.

View full abstract

The positioning required in operations of farm machinery is one of the most fundamental motion. In clarifying the human controllability of positioning, the performance of tracking task to sinusoidal inputs was investigated in the preview control system of pursuit tracking behavior including the controlled element of proportional action. The operator individuality factor and the effect of input properties were studied on responses in steady state tracking tasks.
The results of the experimental study led to the following conclusions.
1) Tracking error was affected significantly by the amplitude and the frequency of sinusoidal inputs. The smaller the input amplitude and the lower the input frequency were, the smaller was the mean absolute error of tracking task.
2) The input property had considerable effects upon the stablity of responses in steady state tracking tasks. The smaller the input amplitude and the lower the input frequency were, the smaller was the standard deviation of cyclic average of mean absolute error.
3) The variation power of tracking error increased in proportion to the input amplitude and was affected by the input frequency.
4) The distributions of the error power spectral density in tracking tasks showed the peak pattern at the input frequency. The variation power of tracking error was dependent on the error power component which was based on the phase shift at the input frequency.
5) As the input frequency increased, the peak value of the normalized error power spectral density decreased and the rate of error power component based on the phase shift to the variation power of tracking error decreased.
6) On the steady state responses like the sinusoidal tracking, the tracking performance was affected significantly by the input property.

View full abstract

The experimental studies were made to find the capability of the precision planting of small and irregular seed with vacuum metering device. The results obtained are as follows.
(1) In case that the direction of the orifice was the same as the movement of the nozzle in the seed box, picking up rate was higher than the other cases. When both directions made a right angle, not only the rate was inferior to that of the same direction, but also higher vacuum pressure was required.
(2) Picking up efficiency was influenced directly by the suction air-flow rate. The adequate amount of suction air-flow to get maximum picking up rate of single seed was found experimentally for the various kind of seeds.
(3) The relation between sectional area (A) of the orifice in the region of 0.4-1.0mm of the diameter and the flow rate (G) of air could be shown as follow.
G=A²√2gγP/0.00087+1.316A
(4) Maximum picking up rate of single seed and adequate amount of the suction air-flow under the various experimental conditions were obtained. (Table 2)
The adequate flow rate of air was approximately relative to the logarithm of the weight of seed. (Fig 11)
Because surface of heavy seed was comparatively smooth, in generally, the leak of airf-low around the seed and adequate amount of air-flow per weight of smooth seed, were not so much. For the coated seed of sugar beet, little double seeds was picked up, and the single seed reached 100per cent for the suction air-flow of more than 0.05g/sec.
(5) Increasing the velocity of nozzle (contact velociy to seed), rate of picking up decreased. This decrease of the rate could be supplemented by increase of flow rate.
It was considered that the ratio (G/v) of the flow rate (G) to get maximum picking up rate of single seed to the velocity (v) of nozzle showed constant value for each kind of seeds.

View full abstract

To design the rice transplanting mechanism consisting of four bar linkage, the method to synthesize with the computer was investigated by analytical method. The condition to required for synthesis was obtained experimentally. The results are as follows.
(1) The path for tip of the tine to sweep was computed repeatedly under changing each link length with random number. The mechanism to satisfy the given condition was searched and by the Monte Carlo synthesis method. By using this method, we can give as condition not only position but position, velocity and the range without passing.
(2) To reform the link mechanism exactly, the method of minimizing the function of several variables was applied. And it was confirmed that this method was practical.
(3) The condition to transplant precisely was obtained from the experiment that was done with young seedling broadcasted, soil bin and the pistoncrank type of transplanting mechanism. As the results, it was necessary to be small the path of tine in the soil and was effective for the case of the velocity of the tine being high.
(4) By the above mentioned synthesis method, five examples of transplanting mechanism consisted with four bar linkage were synthesized with fairly accuracy.

View full abstract

The simulation of valve movement and the computer aided design of suction and discharge valves in power sprayer are described in this report.
These valves have been designed as the result of experiment repeated about the combinations of valve and valve spring.
The main sizes of valve was calculated using the values of maximum, mean and upper and lower limits of confidence limit 95% which was obtained from 39 power sprayers for flow velocity at valve seat. The valve having the maximum volumetric efficiency was designed by the computer simulation in stead of experiments for valve performance in power sprayer.
The following results obtained.
(1) The results of simulation for valve movement almost coincided with those of experiment.
(2) The results of simulation varing spring constants of valve spring were shown in Fig. 5 and 6. When the spring constant was greater, the maximum lift of valve was lower, but the volumetric efficiency of discharge flow simulated between valve and valve seat, was greater.
(3) On the valve spring and valve sizes, the results of calculation by this program and values of supplied model were shown in Table 1. The results of simulation for the valve designed by this program almost coincided with those of experiment on supplied model.
The validity of programing was recognized.

View full abstract

Because of the short drying period of rough rice before tempering stage, the drying is assumed to be carried out mainly from the hull surface. A basic equation was derived assuming the uniform moisture content of the hull, and the well-known laws governing the rate of transfer of mass from a solid to a fluid that was proportional to the difference in vapour pressure between solid surface and fluid. The equilibrium moisture content v. s. relative humidity (water activity) curve was used to estimate the vapour pressure of the hull.
The numerical exact solutions were obtained from the above derived equation and the heat balance equation by Runge-Kutta-Gill method. The approximate analytical solutions were also obtained by the method of linearizing the parameters.
The computed results by the exact and the approximate solutions were in reasonable agreement with the experimental observations in initial five or seven drying range.

View full abstract

The authers supposed that the crak of rice was produced by the strain caused by variation in moisture content at some parts of the rice kernels during drying. In this study, we measured the modulus of elasticity of brown rice by compression test, the shape and the cross sectional area of the brown rice from the X-ray film. For experiments, we selected whole kernels of brown rice (Tosan No. 38), at 14.9, 16.3, 20.5, percent moisture content(W. B.).
The results obtained were as follows;
1. The average cross sectional area of compression test specimens were calculated by Sympsons equation.
2. In the compression test, the stress for the brown rice of low moisture content was larger than that of high moisture content at same strain.
3. The modulus of elasticity of brown rice determined from the linear portion of the stress-strain curve, were found to be 65.7, 52.0, 44.3 and 28.4kg/mm², at respectively 14.9, 16.3, 20.5 and 22.2 percent moisture cotent (W. B.).

View full abstract

Parboiled rice has been known for a long time in some countries of Asia and of Africa, where the people prefer parboiled rice.
The advantage of parboiling treatment comes from the fact that the treatment gelatinizes the rice starch and thus hardens the rice grains. consequently the milling loss is decreased.
The conventional parboiling process consists of soaking of the paddy in cold or lukewarm water for 48 to 72 hours, steaming for 10 to 30 minutes and then drying in the sun. The process has not been standardized to any extent and the produced rice has many disadvantages. Parboiled rice prepared under primitive conditions, has a very dark yellow color, undesirable flavor, aroma, lack of uniformity. Research should be undertaken to study the problems of industrializing and mechanizing the conventional methods for the purpose of improving productions, obtaining products of high quality and increasing commercial value.
This investigation was carried out to produce parboiled rice with a comparatively simple method and to study the effects of parboiling conditions on physicochemical properties by measuring certain changes in rice grains when they were parboiled.
The results of experiments in this report were as follows,
(1) Since soaking paddy in cold or lukewarm water for a long time not only decreased hydrating effects of paddy but made disagreable chnages such as a fermentation in rice grains, soaking should be finished within 24 hours.
(2) Raise of the soaking temperature increased the rate of hydration and kept hydrating effects comparatively long time.
(3) Soaking temperature should be set up below gelatinization temperature of rice starch in order to avoid changes of properties in rice grains.
(4) Prope use of either raw paddy of dried paddy as occasion required had good effects on saving resources and cutting down expenses of processing.

View full abstract

The authors derivated tae differential equation for predicting temperature of drying material from mass and heat transfer balance, and changed it to non-dimensional differential equation. Series solutions were obtained by the method of Frobenius. Both observed and theoretical values were compared, the former was nearly equal to the latter. Conseqently the propriety of theortical solutions were found.
The results obtained were as follows:
1) The material temperature during drying was exactly in accordance with drying air temperature at second critical moisture content M_f2.
2) Theoretical non-dimensional temperature equations were as follows;
a. In the period of falling drying rate,
T_ma=∑^∞_n=1(-1)_n-1(n-1)!A/II^∞_γ=1(A+γD)Qⁿ
b. In the period of falling drying reat,
T_mac=∑^∞_n=1(-1)^n-1(n-1)!A/II^∞_γ=1(A+γD)
3) Authors' theoretical solutions were comparedd with numerical solution by means of Runge-Kutta method, for instance it had relative errors from +0.6 to 4.5, from +0.1 to 4.2% for rough rice and onion, respectively. Then it was found that their theoretical solutions were useful for predicting temperature of drying material.

View full abstract

The objects of this report are to estimate the increase or decrease of Chlorophyll as one of the control factors for the culture management and to use for the automatic control.
The color of leaf surface was determined and the quantity of Chlorophyll per unit leaf area was calculated, then the correlation betweem the both was investigated.
The results were as follows:
1. There were significant-difference at the significance level 0.1% between three ingredient values (L, a, b) in Hunter renotation system, and they had primary correlation.
2. There were high correlations between three ingredient values (L, a, b) and the quantity of Chlorophyll (C).
3. There were high correlations between Hue (b/a or θ), Value (L), Chroma (√a²+b²), as three attributes of colors, and the quantity of Chlorophyll (C).
4. As Hue changed from yellow to green, the quantity of Chlorophyll gradually increased.
5. The quantity of Chlorophyll in dim color was more than in clear color of Chroma.
It would be possible to estimate the increase or decrease of Chlorophyll by the leaf colors.

View full abstract

For the improvement of fruit removal equipment, engineers need a better understanding of the biological and physical properties of citrus fruits to establish their harvester design parameters. The purpose of this research is to obtain quantitative and correlative information about Citrus Unshiu (Satsuma Orange) on detach ment force, torsional moment for shearing stem, coefficient of friction at fruit-rind, the effect of growth regulator on hastening fruit abscission and the qualties of fruits when an external force is exerted upon them.
1) The fruit detachment force by the tensile testing instrument was 3-8kg, average 5.35kg, and the correlation between detachment force and fruit weight (fruit size) was recognized. But the mature Citrus Unshiu's rind was so tender and apt to float that a portion of peel was torn with stem. This was observed more than 50% of total fruits in some variety during detachment. Therefore, it is not suitable for harvesting fruits to detach by only tensile force. The leaf detachment force was 1-2.3kg, average 1.58kg, but leaf removal during vibratory harvesting was nothing to be anxious about, because leaf mass was too small in comparision with fruit mass.
2) In order to accelerate chemical control of fruit abscission, fruits was soaked in Ethrel (2-chloroethyl-phosphonic acid) solusion (48×10^-4mg/l). The effect of Ethrel on detachment increased in proportion to the days elapsed since treatment date, and detachment force became under 2kg 8 days later. This fact may enable us to predict fruit detachment without tearing rind, because the minimum tensile strength of fruit-rind is 2-3kg.
3) Torsional moment used to shear the stem of Citrus Unshiu was 0.5-4.9kg-cm, average 1.1kg-cm, and it correlated with fruit size or stem diameter. If fruits were detached by only torsional operation, about 300 degree of twist angle was required to shear the stem.
4) Statical coefficient of friction between fruit rind of Citrus Unshiu and Acryle sheet, Lauan board was above 0.8. It may be considered to use the frictional resistance of fruit-rind as the binding force to support fruit during detachment operation.
5) When fruits were subjected to drop repeatedly to ground just after sampling, their acid was remarkably decreased and their sugar was increased in proportion to days elapsed since dropping treatment. Therefore, Brix-acid ratio was rapidly increased but the quality of fruits was fast deteriorated, too. These fruits will not be adapted for storage.

View full abstract

Grading of citrus fruits was done by manual sorting based on the external appearance and color. Due to this manual labor within the grading line of citrus, it became quite impossible to increase the sorting rate of fruits together with sortillg efficiency.
From this point of view, it becomes meaningful that an automatic color sorting facility should be planned and manufactured.
Optical reflectance properties of Satsuma Orange, Citrus Unshiu Marc., were investigated to serve the automatic grading in the packing house line.
The results obtained were as follows:
1. Reflectance for distinguishing the degree of peel color should be best measured at near the wavelength of 680nm.
2. The color grade or HUE of Satsuma Orange was found to be directly proportional to the logarithm of chlorophyll content.
Reflectance out put or criterion I₁ due to the measuring wavelength at 680nm was proportional to log (chl.)≡X,
I₁=-0.33X+0.29(-1.4≤X≤0.9)
3. The criterion I₁ was also found to be proportional to the illuminated area on the glass sphere filled with milk solution.
I₁=0.023A(A≤30cm²)
4. To eliminate the effect of size variation and apparatus sensitivity, measurements of reflectance were made in regard to couple of wavelength.
One wavelength must be sensitive to chlorophyll content, another must be insensitive to it. This new color criterion I₂ was expressed as
I₂(λ₁λ₂)=C(λ₁)R(λ₁)A/C(λ₂)R(λ₂A)=KR(λ₁)/R(λ₂)
The measuring and reference wavelengths of one possible conbination was 680nm and 740nm, respectively.
The regression equation is:
I₂=-0.43X+0.38, r=0.97
5. The effect of peel treatments, in the packing house line, on the value of criterion I₂ was almost negligible.
6. Graphical representation of correlation coefficients of the possible combinations of reflectance intensity ratio (I₂) with the chlorophyll content as in fig. (8), is shown in fig. (10).

View full abstract

It was researched in the variation of spinach temperature, during the air-precooling, then in ordinary truk-shipping from the cooling room in the producing district to the wholesale market in the consuming city, and before auction after arrival at the market, the following results were obtained.
1. The sufficient pre-cooling time in nonvented carton (46.5×36×15cm) in stack and in condition with enough exposure of carton to cooling-air was upward of one day.
2. The relationshp between opening ratio (ratio of the area of vent holes to carton) and half cooling time described with hyperbolic curves.
3. The position of vent holes has effects upon the cooling rate, the effectiveness of vent holes in parallel planes was remarkable more than only one plane.
4. Flowing cooling air at an angle of 45° approximately to plane with vent holes was the best effect, its half cooling time was about 2/3 of one of the parallel flow.
5. The cooling rate of non-packing spinach was fast, if the system in cargo booking and shipment is improved, air-precooling seems to be useful enough.
6. Loading and unloading by man-handling seems not to cause a special rise of temperature.
7. Transporting load covered with a 5mm thick mat made of Urethane-form for keeping at low temperature by truck, spinach temperature of about half load was about 16°C after 10 hours from shipment, then at auction the temperature of considerable spinach became over 20°C.
8. The location of the mass-average temperature in a rectangle was found by the following equation,
cosx/2aπ·cosy/2bπ=0.405
therefore, for instance, it find the location of the mass average temperature of rectangular prism being able to regard the conduction of heat as twe-dimensional at the distance 27% from the center in surface plane to the center of the prism.

View full abstract

Characteristics of power requirements, torque fluctuation of the rotor, air velocity distribution in the chute and chopping lengths of the materials were studied on the direct-throw flail-type forage harvester. Also the influence of the operating condition and the crop condition upon the chopping length was investigated using the model of cutting mechanism.
1) Power requirements of the flail rotor increased linearly as the material throughput was increased and varied with the kind of crops and their growth stages. From distributions of power requirements the blowing air horsepower occupied 35-45% of the total power.
2. Concerning torque fluctuations of the rotor the amplitudes were large resulting from the knife rows arrangements and veriating throughputs of the materials. From the spectral analysis of torque the frequencies of fluctuation were mainly due to the revolution speed of the rotor and its duplicated frequencies of the symmetrically arranged knife row.
3) At the throughput of 15t/hr or more, blowing up the materials was not enough even in harvesting the green crops due to the lower air velocities in the chute.
4) From the distribution of chopped lengths those of about 10cm long were counted comparatively many. However, the longer materials of 30-40cm were observed considerably. The distribution pointed out the characteristic of wide range. Analysis of cutting mechanism clarified that long stalks increased with the increase of cutting pitch V/n and of standing heights.

View full abstract

(1) This experiment was conducted to observe some physical and thermal characeristics of rolled hay wafer dried by the micro-wave heating.
(2) The drying process was divided into three periods; pre-heating period, constant drying-rate peried, and falling drying-rate period. The pre-heating time was in proportion to the initial water equivalent of the material. The drying process of the material shifted sharply from the pre-heating period to the constant-rate drying, and changed to the falling-rate drying at the moisture content about 8.7% (w, b.), and finally became to the bone-dry condition. Comparing with the heated-air drying, the constant drying-rate period occupied the major portion of drying process.
(3) During the constant drying-rate period, the material was isothermally dried, approxmiately 100°C, the moitsure was evaporated by boiling, and then moved out. In this experiment, it seemed that the drying-rate of the material did not depend on the apparent density of the dry matter and the initial moisture content of the material, and it was mainly influenced by the micro-wave out put of the energy source.
(4) Moisture at any position of the material, center, medium, and surface, was evaporated uniformly, and moved out. However it seemed that a little variance existed because of the nonuniformity of the energy field in the cavity, and it could not be measured.
(5) The vapor transfered in the material and moved out by the gradient of the partial pressure of the vapor so it was considered that the resistance to the vapor transfer was ver ylow. The resistance to the vapor transfer in the axial direction was lower than that in the radial one.
(6) The heat does not transfer easily from the surface to the center of the material by the heated air drying. But by the micro-wave heating, the heat is generated uniformly was the material, so the amount of moisture which was equivalent to the micro-wave out put could be evaporated.

View full abstract

In order to recover the exhaust-air-enthalpy of a heated-air-drier and utilize it for heating the inlet-air, a heat-pump and the exhaust-air-reculation with this pump were used in this method. From the experimental results it was clear that most of the heat lost by the exhaust-air including the latent-heat of vaporization of the grain-moisture was recovered.
(1) Experimental models and plot are illustrated in Fig. 2 and Tab. 2. Five experiments were conducted including an experiment using a heater without heat-pump. From the change of air-state, the flow and balance of the water and energy were obtained, then the energy-efficiency of drying was discussed.
(2) In case of recovering the exhaust-enthalpy by the heat-pump only, [system (A)], it was possible to decrease the enthalpy of the exhaust-air. Tower than that of the inlet-air and discharge it. Therefore it was also possible to pump up the heat of the atmosphere into the system during the first stage of drying-period.
(3) When the recovering-heat-capacity of the heat-pump was lower than the exhaust-enthalpy, the method of using the exhaust-air-recirculation with the heat-pump, [system (C), (D)], was effective. The heat was accumulated in the system, the air-humidity and enthalpy became higher, and because the water is taken out from the system by the evaporator, then the air-humidity became lower. In case of the exhaust-air-recirculation without controlling the temperature, [system (C)], the air-temperature became high, and the drying-rate did not fall although the air-humidity was high.
In case of controlling the air-temperature at 45°C, [system (D)], because of the exhaust-air-recirculation, the drying-rate decreased but and the energy supplied from the heater to control the air-temperature was reduced.
(4) The capacity of the heat-pump used in this test was small, so that the coefficient of performance per watt-consumption was about 2. In case of the heat-pump, without heater, [system (A), (C)], the energy-efficiency of drying was about twice of that of using the heater without heat-pump.
(5) With this method, the energy can be educed, and it is possible to avoid the inconvenience of using oil and the effect of stink on grain. In case of using the exhaust-air-recirculation with the heat-pump, supposing that the condensed-water is within the system, this will be a closed system and the dust will not be scattered. A heat-pump is more expensive than an oilburner. Therefore it is necessary to apply a heat-pump for coolin-gstorage after drying in practice.
(6) In order to increase the energy-efficiency of drying, it is necessary to improve the insulation of the equipment and the performance of the heat-pump as wall as the enlargement of the scale and the usability of the multiple-effect-compression-method. From point of view of fuelcost in Japan now, the energy-efficiency required for drying by electricity will be 4-5 times that of using petroleum.

View full abstract