37 Evaluation and Improvement Proposals for a Business Facility …
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adsorption chiller, and as a result, the number of heat collectors can be reduced to
five. In addition, as for the angle, as a result of considering heat collection in the
intermediate period and safety aspects, it will be maintained at the current angle
without changing from 15°.
37.5 Discussions
37.5.1 Solar Heat Collector Working Procedure
Solar heat is generally used for air conditioning in the winter time and as hot water
supply throughout the year. According to a NEDO survey, solar heat utiliziation is
mainly for hot water supply (78%), and room heating (43%) (Agency for Natural
Resources and Energy 2019a, b, c) In addition, the solar heat collectors are considered more effective for these purposes because they have a higher energy utilization
efficiency (50–60%) compared to the power generation efficiency of solar power
generation. The down side of solar heat collector is that heat can only be transported
in limited ways compared to electricity. In the hybrid system discussed in this study,
the surplus solar heat could not be consumed by the adsorption refrigerator, and as a
result, half of the solar heat collectors have stopped working. Moreover, since solar
heat is an unstable supply, it is necessary to put in a separate hot water supply system
as a backup. It should not be expected that solar heat will cover the whole amount of
heat demand. Therefore, in order to improve the energy utilization rate of the system,
it is important to supply only the amount that can be used as the capacity of the solar
heat collector. The energy utilization rate when the solar collector is set to 5 and the
adsorption refrigerator is removed is shown in Fig. 37.19. In the calculation, the heat
collection amount before the change is assumed to be 16 sheets. As for heat loss
and pressure loss in the piping, it was assumed that there are about 30% of loss in
the winter time. The annual heat use had decreased by 2.5%, but the average energy
utilization rate had improved by 15%. In addition, because the installation area of the
solar heat collector and adsorption chiller can be reduced (11 solar heat collectors ×
11.9 m
2 plus adsorption chiller approximately 1 square), there was about 131.9 m
2
reduction. According to the 2016 heat supply business manual (Japan Heat Supply
Business Association 2016), the unit price of heat supply is 7.01 yen/MJ in the Kanto
region, and the revenue decreases by 149,374 yen per year due to the decrease in hot
water supply. Furthermore, as the site rent of 131.9 m
2 can be reduced, 2.4 million
yen can be saved. From the viewpoint of cost evaluation, it was found that it would
be more cost effective to set the capacity precisely in order to avoid heat collection
surplus rather than to have it at its maximum capacity (Figs. 37.17, 37.18).
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adsorption chiller, and as a result, the number of heat collectors can be reduced to
five. In addition, as for the angle, as a result of considering heat collection in the
intermediate period and safety aspects, it will be maintained at the current angle
without changing from 15°.
37.5 Discussions
37.5.1 Solar Heat Collector Working Procedure
Solar heat is generally used for air conditioning in the winter time and as hot water
supply throughout the year. According to a NEDO survey, solar heat utiliziation is
mainly for hot water supply (78%), and room heating (43%) (Agency for Natural
Resources and Energy 2019a, b, c) In addition, the solar heat collectors are considered more effective for these purposes because they have a higher energy utilization
efficiency (50–60%) compared to the power generation efficiency of solar power
generation. The down side of solar heat collector is that heat can only be transported
in limited ways compared to electricity. In the hybrid system discussed in this study,
the surplus solar heat could not be consumed by the adsorption refrigerator, and as a
result, half of the solar heat collectors have stopped working. Moreover, since solar
heat is an unstable supply, it is necessary to put in a separate hot water supply system
as a backup. It should not be expected that solar heat will cover the whole amount of
heat demand. Therefore, in order to improve the energy utilization rate of the system,
it is important to supply only the amount that can be used as the capacity of the solar
heat collector. The energy utilization rate when the solar collector is set to 5 and the
adsorption refrigerator is removed is shown in Fig. 37.19. In the calculation, the heat
collection amount before the change is assumed to be 16 sheets. As for heat loss
and pressure loss in the piping, it was assumed that there are about 30% of loss in
the winter time. The annual heat use had decreased by 2.5%, but the average energy
utilization rate had improved by 15%. In addition, because the installation area of the
solar heat collector and adsorption chiller can be reduced (11 solar heat collectors ×
11.9 m
2 plus adsorption chiller approximately 1 square), there was about 131.9 m
2
reduction. According to the 2016 heat supply business manual (Japan Heat Supply
Business Association 2016), the unit price of heat supply is 7.01 yen/MJ in the Kanto
region, and the revenue decreases by 149,374 yen per year due to the decrease in hot
water supply. Furthermore, as the site rent of 131.9 m
2 can be reduced, 2.4 million
yen can be saved. From the viewpoint of cost evaluation, it was found that it would
be more cost effective to set the capacity precisely in order to avoid heat collection
surplus rather than to have it at its maximum capacity (Figs. 37.17, 37.18).