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Multi-tank, Temperature Stratification Type of Heat Storage System: Frequently Asked Questions
Q1. What is the principle of this gtemperature stratification type of heat storage tankh?

A1. Water produces buoyant force due to density variations with temperatures. In other words, in a stationary tank, warmed-up water (12 dec C) has lower density than that of chilled water (5 dec C) and moves upward (i.e., forms stratification). If the flow velocity is designed by reducing the inlet velocity enough not to damage stratification formed due to the density variations, the temperature stratification can be formed, even though the system is of multi-tank type. Consequently, heat storage and radiation with less mixing loss can be achieved.

Q2. What is the conventional type of heat storage tank, not of temperature stratification type?
A2. It is referred to gConnection pipe typeh, on which water inlets and outlets of each tank are generally arranged in a staggered configuration. The efficiency is said to be approximately 60%.
Temperature stratification type
Connection pipe type
Q3. What precautions should be taken when making a proposal?

A3. Each heat storage tank divided should have approximately same capacity (water volume) and arranged in parallel.

Q4. If this system applicable to not only chilled water but also hot water?

A4. Yes, it is applicable (but no accomplishments yet). In order to apply to hot water, however, directions of water inlet and outlet should be reversed.

Q5. Does this system cause a substantial increase in the costs?

A5. No, not much, if the introduction of build-up type heat storage tank was originally planned and the waterproofing heat insulation work was included in the plan. Aside from the waterproofing heat insulation work, the initial costs increase by approximately 200,000 yen per tank. Through the use of PVC header pipes and distributors, the costs are brought in line. Furthermore, providing no flow control mechanism also helps cut the initial costs and maintenance costs. Even though the initial costs increase, the capacity possible to be stored substantially increases and the use of low-cost nighttime power also increases in portion. As a result, the increase in the initial costs can be recovered in one to three years.


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