Exergy Lab

Use case · Energy and process models

Work through a heat or mass balance, step by step

Elta can talk you through an energy or process model out loud. It follows the balance with you, says which property data and assumptions sit behind each step, and points out where a number would need a different basis before you lean on it.

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How do I work through a heat balance with Elta?

Share the model, then ask Elta to walk through the balance step by step. It follows the heat given up by the hot stream and taken by the cold stream, says which specific heats and temperatures it used, and points to any step where an assumption is doing a lot of work.

  1. Share the spreadsheet or page that holds the balance.
  2. Ask Elta to say the property data, the basis and the assumptions for each stream.
  3. Have it work out each duty and compare the hot side with the cold side.
  4. Close any gap: a unit slip, a missing loss, or an assumption you did not mean to make.

What does a closed heat balance look like?

In a steady heat balance, the heat released by the hot stream equals the heat absorbed by the cold stream plus the heat lost to the surroundings. When the two sides do not match, the gap usually comes from a unit, a flow rate, a property value or a loss nobody wrote down.

Worked example. Hot water at 2 kg/s cools from 85 to 60 degrees Celsius with a specific heat of 4.18 kJ/(kg·K), releasing 2 × 4.18 × 25 = 209 kW. Cold water at 1.5 kg/s absorbs that same 209 kW, so its temperature rises by 209 ÷ (1.5 × 4.18) = 33.3 K.

Elta says the specific heat out loud as an assumption, notes that it treats it as constant over this range, and asks you to confirm before you rely on the outlet temperature.

Which assumptions matter most in an energy model?

Property values, the reference state, the basis of fuel energy and the treatment of losses matter most. A constant specific heat is fine over a small range and a poor fit over a large one. Elta names each assumption so you can decide whether it holds for your case.

  • Constant or temperature-dependent specific heat.
  • Higher or lower heating value for fuels.
  • Reference temperature and pressure.
  • Heat losses to the surroundings, included or ignored.

How is Elta different from a process simulator?

A process simulator builds and solves a full model. Elta works alongside whatever you already use: it reads your model or spreadsheet, talks through each stream and step, and helps you catch slips and test assumptions early. Many engineers use the two together, one to build and one to think out loud with.

Frequently asked questions

Can Elta help with property data?

Elta tells you the property values it uses so you can compare them with your reference tables for the conditions in your model.

Does Elta understand exergy as well as energy?

Exergy Lab, the company behind Elta, is built around the difference between how much energy you have and what it can do. For the background, read our research article Why All Joules Are Not Equal.

Can I talk through the model instead of typing?

Yes. Elta is voice-first: speak naturally, interrupt, and ask follow-ups while it works through the balance with you.

Can Elta help me set up a new balance from scratch?

Yes. Describe the streams and what you are trying to find out, and Elta can help you lay out the balance, choose sensible assumptions and talk through each step.

What can Elta see?

Only what you choose to share: a screen, a window, a tab or an image. You can stop sharing or end a session whenever you like.

Is Elta free to try?

Yes. The Free plan includes Elta and the Voice Agent with 100,000 tokens a day, and no credit card is needed. Upgrade to Plus or Pro whenever you want more room.