Name the calorimeter used to measure `Delta U`.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the calorimeter used to measure the change in internal energy (ΔU).

2. **Identifying the Calorimeter**: The calorimeter specifically designed to measure ΔU is known as the **bomb calorimeter**.

3. **Mechanism of the Bomb Calorimeter**:
- The bomb calorimeter operates at constant volume, which is essential for measuring the change in internal energy accurately.
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